1. 09 Oct, 2018 32 commits
    • Suraj Jitindar Singh's avatar
      KVM: PPC: Book3S HV: Handle differing endianness for H_ENTER_NESTED · 10b5022d
      Suraj Jitindar Singh authored
      The hcall H_ENTER_NESTED takes two parameters: the address in L1 guest
      memory of a hv_regs struct and the address of a pt_regs struct.  The
      hcall requests the L0 hypervisor to use the register values in these
      structs to run a L2 guest and to return the exit state of the L2 guest
      in these structs.  These are in the endianness of the L1 guest, rather
      than being always big-endian as is usually the case for PAPR
      hypercalls.
      
      This is convenient because it means that the L1 guest can pass the
      address of the regs field in its kvm_vcpu_arch struct.  This also
      improves performance slightly by avoiding the need for two copies of
      the pt_regs struct.
      
      When reading/writing these structures, this patch handles the case
      where the endianness of the L1 guest differs from that of the L0
      hypervisor, by byteswapping the structures after reading and before
      writing them back.
      
      Since all the fields of the pt_regs are of the same type, i.e.,
      unsigned long, we treat it as an array of unsigned longs.  The fields
      of struct hv_guest_state are not all the same, so its fields are
      byteswapped individually.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarSuraj Jitindar Singh <sjitindarsingh@gmail.com>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      10b5022d
    • Suraj Jitindar Singh's avatar
      KVM: PPC: Book3S HV: Sanitise hv_regs on nested guest entry · 73937deb
      Suraj Jitindar Singh authored
      restore_hv_regs() is used to copy the hv_regs L1 wants to set to run the
      nested (L2) guest into the vcpu structure. We need to sanitise these
      values to ensure we don't let the L1 guest hypervisor do things we don't
      want it to.
      
      We don't let data address watchpoints or completed instruction address
      breakpoints be set to match in hypervisor state.
      
      We also don't let L1 enable features in the hypervisor facility status
      and control register (HFSCR) for L2 which we have disabled for L1. That
      is L2 will get the subset of features which the L0 hypervisor has
      enabled for L1 and the features L1 wants to enable for L2. This could
      mean we give L1 a hypervisor facility unavailable interrupt for a
      facility it thinks it has enabled, however it shouldn't have enabled a
      facility it itself doesn't have for the L2 guest.
      
      We sanitise the registers when copying in the L2 hv_regs. We don't need
      to sanitise when copying back the L1 hv_regs since these shouldn't be
      able to contain invalid values as they're just what was copied out.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarSuraj Jitindar Singh <sjitindarsingh@gmail.com>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      73937deb
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Add one-reg interface to virtual PTCR register · 30323418
      Paul Mackerras authored
      This adds a one-reg register identifier which can be used to read and
      set the virtual PTCR for the guest.  This register identifies the
      address and size of the virtual partition table for the guest, which
      contains information about the nested guests under this guest.
      
      Migrating this value is the only extra requirement for migrating a
      guest which has nested guests (assuming of course that the destination
      host supports nested virtualization in the kvm-hv module).
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      30323418
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Don't access HFSCR, LPIDR or LPCR when running nested · f3c99f97
      Paul Mackerras authored
      When running as a nested hypervisor, this avoids reading hypervisor
      privileged registers (specifically HFSCR, LPIDR and LPCR) at startup;
      instead reasonable default values are used.  This also avoids writing
      LPIDR in the single-vcpu entry/exit path.
      
      Also, this removes the check for CPU_FTR_HVMODE in kvmppc_mmu_hv_init()
      since its only caller already checks this.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      f3c99f97
    • Suraj Jitindar Singh's avatar
      KVM: PPC: Book3S HV: Invalidate TLB when nested vcpu moves physical cpu · 9d0b048d
      Suraj Jitindar Singh authored
      This is only done at level 0, since only level 0 knows which physical
      CPU a vcpu is running on.  This does for nested guests what L0 already
      did for its own guests, which is to flush the TLB on a pCPU when it
      goes to run a vCPU there, and there is another vCPU in the same VM
      which previously ran on this pCPU and has now started to run on another
      pCPU.  This is to handle the situation where the other vCPU touched
      a mapping, moved to another pCPU and did a tlbiel (local-only tlbie)
      on that new pCPU and thus left behind a stale TLB entry on this pCPU.
      
      This introduces a limit on the the vcpu_token values used in the
      H_ENTER_NESTED hcall -- they must now be less than NR_CPUS.
      
      [paulus@ozlabs.org - made prev_cpu array be short[] to reduce
       memory consumption.]
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarSuraj Jitindar Singh <sjitindarsingh@gmail.com>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      9d0b048d
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Use hypercalls for TLB invalidation when nested · 690ed4ca
      Paul Mackerras authored
      This adds code to call the H_TLB_INVALIDATE hypercall when running as
      a guest, in the cases where we need to invalidate TLBs (or other MMU
      caches) as part of managing the mappings for a nested guest.  Calling
      H_TLB_INVALIDATE lets the nested hypervisor inform the parent
      hypervisor about changes to partition-scoped page tables or the
      partition table without needing to do hypervisor-privileged tlbie
      instructions.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      690ed4ca
    • Suraj Jitindar Singh's avatar
      KVM: PPC: Book3S HV: Implement H_TLB_INVALIDATE hcall · e3b6b466
      Suraj Jitindar Singh authored
      When running a nested (L2) guest the guest (L1) hypervisor will use
      the H_TLB_INVALIDATE hcall when it needs to change the partition
      scoped page tables or the partition table which it manages.  It will
      use this hcall in the situations where it would use a partition-scoped
      tlbie instruction if it were running in hypervisor mode.
      
      The H_TLB_INVALIDATE hcall can invalidate different scopes:
      
      Invalidate TLB for a given target address:
      - This invalidates a single L2 -> L1 pte
      - We need to invalidate any L2 -> L0 shadow_pgtable ptes which map the L2
        address space which is being invalidated. This is because a single
        L2 -> L1 pte may have been mapped with more than one pte in the
        L2 -> L0 page tables.
      
      Invalidate the entire TLB for a given LPID or for all LPIDs:
      - Invalidate the entire shadow_pgtable for a given nested guest, or
        for all nested guests.
      
      Invalidate the PWC (page walk cache) for a given LPID or for all LPIDs:
      - We don't cache the PWC, so nothing to do.
      
      Invalidate the entire TLB, PWC and partition table for a given/all LPIDs:
      - Here we re-read the partition table entry and remove the nested state
        for any nested guest for which the first doubleword of the partition
        table entry is now zero.
      
      The H_TLB_INVALIDATE hcall takes as parameters the tlbie instruction
      word (of which only the RIC, PRS and R fields are used), the rS value
      (giving the lpid, where required) and the rB value (giving the IS, AP
      and EPN values).
      
      [paulus@ozlabs.org - adapted to having the partition table in guest
      memory, added the H_TLB_INVALIDATE implementation, removed tlbie
      instruction emulation, reworded the commit message.]
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarSuraj Jitindar Singh <sjitindarsingh@gmail.com>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      e3b6b466
    • Suraj Jitindar Singh's avatar
      KVM: PPC: Book3S HV: Introduce rmap to track nested guest mappings · 8cf531ed
      Suraj Jitindar Singh authored
      When a host (L0) page which is mapped into a (L1) guest is in turn
      mapped through to a nested (L2) guest we keep a reverse mapping (rmap)
      so that these mappings can be retrieved later.
      
      Whenever we create an entry in a shadow_pgtable for a nested guest we
      create a corresponding rmap entry and add it to the list for the
      L1 guest memslot at the index of the L1 guest page it maps. This means
      at the L1 guest memslot we end up with lists of rmaps.
      
      When we are notified of a host page being invalidated which has been
      mapped through to a (L1) guest, we can then walk the rmap list for that
      guest page, and find and invalidate all of the corresponding
      shadow_pgtable entries.
      
      In order to reduce memory consumption, we compress the information for
      each rmap entry down to 52 bits -- 12 bits for the LPID and 40 bits
      for the guest real page frame number -- which will fit in a single
      unsigned long.  To avoid a scenario where a guest can trigger
      unbounded memory allocations, we scan the list when adding an entry to
      see if there is already an entry with the contents we need.  This can
      occur, because we don't ever remove entries from the middle of a list.
      
      A struct nested guest rmap is a list pointer and an rmap entry;
      ----------------
      | next pointer |
      ----------------
      | rmap entry   |
      ----------------
      
      Thus the rmap pointer for each guest frame number in the memslot can be
      either NULL, a single entry, or a pointer to a list of nested rmap entries.
      
      gfn	 memslot rmap array
       	-------------------------
       0	| NULL			|	(no rmap entry)
       	-------------------------
       1	| single rmap entry	|	(rmap entry with low bit set)
       	-------------------------
       2	| list head pointer	|	(list of rmap entries)
       	-------------------------
      
      The final entry always has the lowest bit set and is stored in the next
      pointer of the last list entry, or as a single rmap entry.
      With a list of rmap entries looking like;
      
      -----------------	-----------------	-------------------------
      | list head ptr	| ----> | next pointer	| ---->	| single rmap entry	|
      -----------------	-----------------	-------------------------
      			| rmap entry	|	| rmap entry		|
      			-----------------	-------------------------
      Signed-off-by: default avatarSuraj Jitindar Singh <sjitindarsingh@gmail.com>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      8cf531ed
    • Suraj Jitindar Singh's avatar
      KVM: PPC: Book3S HV: Handle page fault for a nested guest · fd10be25
      Suraj Jitindar Singh authored
      Consider a normal (L1) guest running under the main hypervisor (L0),
      and then a nested guest (L2) running under the L1 guest which is acting
      as a nested hypervisor. L0 has page tables to map the address space for
      L1 providing the translation from L1 real address -> L0 real address;
      
      	L1
      	|
      	| (L1 -> L0)
      	|
      	----> L0
      
      There are also page tables in L1 used to map the address space for L2
      providing the translation from L2 real address -> L1 read address. Since
      the hardware can only walk a single level of page table, we need to
      maintain in L0 a "shadow_pgtable" for L2 which provides the translation
      from L2 real address -> L0 real address. Which looks like;
      
      	L2				L2
      	|				|
      	| (L2 -> L1)			|
      	|				|
      	----> L1			| (L2 -> L0)
      	      |				|
      	      | (L1 -> L0)		|
      	      |				|
      	      ----> L0			--------> L0
      
      When a page fault occurs while running a nested (L2) guest we need to
      insert a pte into this "shadow_pgtable" for the L2 -> L0 mapping. To
      do this we need to:
      
      1. Walk the pgtable in L1 memory to find the L2 -> L1 mapping, and
         provide a page fault to L1 if this mapping doesn't exist.
      2. Use our L1 -> L0 pgtable to convert this L1 address to an L0 address,
         or try to insert a pte for that mapping if it doesn't exist.
      3. Now we have a L2 -> L0 mapping, insert this into our shadow_pgtable
      
      Once this mapping exists we can take rc faults when hardware is unable
      to automatically set the reference and change bits in the pte. On these
      we need to:
      
      1. Check the rc bits on the L2 -> L1 pte match, and otherwise reflect
         the fault down to L1.
      2. Set the rc bits in the L1 -> L0 pte which corresponds to the same
         host page.
      3. Set the rc bits in the L2 -> L0 pte.
      
      As we reuse a large number of functions in book3s_64_mmu_radix.c for
      this we also needed to refactor a number of these functions to take
      an lpid parameter so that the correct lpid is used for tlb invalidations.
      The functionality however has remained the same.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarSuraj Jitindar Singh <sjitindarsingh@gmail.com>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      fd10be25
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Handle hypercalls correctly when nested · 4bad7779
      Paul Mackerras authored
      When we are running as a nested hypervisor, we use a hypercall to
      enter the guest rather than code in book3s_hv_rmhandlers.S.  This means
      that the hypercall handlers listed in hcall_real_table never get called.
      There are some hypercalls that are handled there and not in
      kvmppc_pseries_do_hcall(), which therefore won't get processed for
      a nested guest.
      
      To fix this, we add cases to kvmppc_pseries_do_hcall() to handle those
      hypercalls, with the following exceptions:
      
      - The HPT hypercalls (H_ENTER, H_REMOVE, etc.) are not handled because
        we only support radix mode for nested guests.
      
      - H_CEDE has to be handled specially because the cede logic in
        kvmhv_run_single_vcpu assumes that it has been processed by the time
        that kvmhv_p9_guest_entry() returns.  Therefore we put a special
        case for H_CEDE in kvmhv_p9_guest_entry().
      
      For the XICS hypercalls, if real-mode processing is enabled, then the
      virtual-mode handlers assume that they are being called only to finish
      up the operation.  Therefore we turn off the real-mode flag in the XICS
      code when running as a nested hypervisor.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      4bad7779
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Use XICS hypercalls when running as a nested hypervisor · f3c18e93
      Paul Mackerras authored
      This adds code to call the H_IPI and H_EOI hypercalls when we are
      running as a nested hypervisor (i.e. without the CPU_FTR_HVMODE cpu
      feature) and we would otherwise access the XICS interrupt controller
      directly or via an OPAL call.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      f3c18e93
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Nested guest entry via hypercall · 360cae31
      Paul Mackerras authored
      This adds a new hypercall, H_ENTER_NESTED, which is used by a nested
      hypervisor to enter one of its nested guests.  The hypercall supplies
      register values in two structs.  Those values are copied by the level 0
      (L0) hypervisor (the one which is running in hypervisor mode) into the
      vcpu struct of the L1 guest, and then the guest is run until an
      interrupt or error occurs which needs to be reported to L1 via the
      hypercall return value.
      
      Currently this assumes that the L0 and L1 hypervisors are the same
      endianness, and the structs passed as arguments are in native
      endianness.  If they are of different endianness, the version number
      check will fail and the hcall will be rejected.
      
      Nested hypervisors do not support indep_threads_mode=N, so this adds
      code to print a warning message if the administrator has set
      indep_threads_mode=N, and treat it as Y.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      360cae31
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Framework and hcall stubs for nested virtualization · 8e3f5fc1
      Paul Mackerras authored
      This starts the process of adding the code to support nested HV-style
      virtualization.  It defines a new H_SET_PARTITION_TABLE hypercall which
      a nested hypervisor can use to set the base address and size of a
      partition table in its memory (analogous to the PTCR register).
      On the host (level 0 hypervisor) side, the H_SET_PARTITION_TABLE
      hypercall from the guest is handled by code that saves the virtual
      PTCR value for the guest.
      
      This also adds code for creating and destroying nested guests and for
      reading the partition table entry for a nested guest from L1 memory.
      Each nested guest has its own shadow LPID value, different in general
      from the LPID value used by the nested hypervisor to refer to it.  The
      shadow LPID value is allocated at nested guest creation time.
      
      Nested hypervisor functionality is only available for a radix guest,
      which therefore means a radix host on a POWER9 (or later) processor.
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      8e3f5fc1
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Use kvmppc_unmap_pte() in kvm_unmap_radix() · f0f825f0
      Paul Mackerras authored
      kvmppc_unmap_pte() does a sequence of operations that are open-coded in
      kvm_unmap_radix().  This extends kvmppc_unmap_pte() a little so that it
      can be used by kvm_unmap_radix(), and makes kvm_unmap_radix() call it.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      f0f825f0
    • Suraj Jitindar Singh's avatar
      KVM: PPC: Book3S HV: Refactor radix page fault handler · 04bae9d5
      Suraj Jitindar Singh authored
      The radix page fault handler accounts for all cases, including just
      needing to insert a pte.  This breaks it up into separate functions for
      the two main cases; setting rc and inserting a pte.
      
      This allows us to make the setting of rc and inserting of a pte
      generic for any pgtable, not specific to the one for this guest.
      
      [paulus@ozlabs.org - reduced diffs from previous code]
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarSuraj Jitindar Singh <sjitindarsingh@gmail.com>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      04bae9d5
    • Suraj Jitindar Singh's avatar
      KVM: PPC: Book3S HV: Make kvmppc_mmu_radix_xlate process/partition table agnostic · 9811c78e
      Suraj Jitindar Singh authored
      kvmppc_mmu_radix_xlate() is used to translate an effective address
      through the process tables. The process table and partition tables have
      identical layout. Exploit this fact to make the kvmppc_mmu_radix_xlate()
      function able to translate either an effective address through the
      process tables or a guest real address through the partition tables.
      
      [paulus@ozlabs.org - reduced diffs from previous code]
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarSuraj Jitindar Singh <sjitindarsingh@gmail.com>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      9811c78e
    • Suraj Jitindar Singh's avatar
      KVM: PPC: Book3S HV: Clear partition table entry on vm teardown · 89329c0b
      Suraj Jitindar Singh authored
      When destroying a VM we return the LPID to the pool, however we never
      zero the partition table entry. This is instead done when we reallocate
      the LPID.
      
      Zero the partition table entry on VM teardown before returning the LPID
      to the pool. This means if we were running as a nested hypervisor the
      real hypervisor could use this to determine when it can free resources.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarSuraj Jitindar Singh <sjitindarsingh@gmail.com>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      89329c0b
    • Paul Mackerras's avatar
      KVM: PPC: Use ccr field in pt_regs struct embedded in vcpu struct · fd0944ba
      Paul Mackerras authored
      When the 'regs' field was added to struct kvm_vcpu_arch, the code
      was changed to use several of the fields inside regs (e.g., gpr, lr,
      etc.) but not the ccr field, because the ccr field in struct pt_regs
      is 64 bits on 64-bit platforms, but the cr field in kvm_vcpu_arch is
      only 32 bits.  This changes the code to use the regs.ccr field
      instead of cr, and changes the assembly code on 64-bit platforms to
      use 64-bit loads and stores instead of 32-bit ones.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      fd0944ba
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Add a debugfs file to dump radix mappings · 9a94d3ee
      Paul Mackerras authored
      This adds a file called 'radix' in the debugfs directory for the
      guest, which when read gives all of the valid leaf PTEs in the
      partition-scoped radix tree for a radix guest, in human-readable
      format.  It is analogous to the existing 'htab' file which dumps
      the HPT entries for a HPT guest.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      9a94d3ee
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Handle hypervisor instruction faults better · 32eb150a
      Paul Mackerras authored
      Currently the code for handling hypervisor instruction page faults
      passes 0 for the flags indicating the type of fault, which is OK in
      the usual case that the page is not mapped in the partition-scoped
      page tables.  However, there are other causes for hypervisor
      instruction page faults, such as not being to update a reference
      (R) or change (C) bit.  The cause is indicated in bits in HSRR1,
      including a bit which indicates that the fault is due to not being
      able to write to a page (for example to update an R or C bit).
      Not handling these other kinds of faults correctly can lead to a
      loop of continual faults without forward progress in the guest.
      
      In order to handle these faults better, this patch constructs a
      "DSISR-like" value from the bits which DSISR and SRR1 (for a HISI)
      have in common, and passes it to kvmppc_book3s_hv_page_fault() so
      that it knows what caused the fault.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      32eb150a
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Streamlined guest entry/exit path on P9 for radix guests · 95a6432c
      Paul Mackerras authored
      This creates an alternative guest entry/exit path which is used for
      radix guests on POWER9 systems when we have indep_threads_mode=Y.  In
      these circumstances there is exactly one vcpu per vcore and there is
      no coordination required between vcpus or vcores; the vcpu can enter
      the guest without needing to synchronize with anything else.
      
      The new fast path is implemented almost entirely in C in book3s_hv.c
      and runs with the MMU on until the guest is entered.  On guest exit
      we use the existing path until the point where we are committed to
      exiting the guest (as distinct from handling an interrupt in the
      low-level code and returning to the guest) and we have pulled the
      guest context from the XIVE.  At that point we check a flag in the
      stack frame to see whether we came in via the old path and the new
      path; if we came in via the new path then we go back to C code to do
      the rest of the process of saving the guest context and restoring the
      host context.
      
      The C code is split into separate functions for handling the
      OS-accessible state and the hypervisor state, with the idea that the
      latter can be replaced by a hypercall when we implement nested
      virtualization.
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      [mpe: Fix CONFIG_ALTIVEC=n build]
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      95a6432c
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Call kvmppc_handle_exit_hv() with vcore unlocked · 53655ddd
      Paul Mackerras authored
      Currently kvmppc_handle_exit_hv() is called with the vcore lock held
      because it is called within a for_each_runnable_thread loop.
      However, we already unlock the vcore within kvmppc_handle_exit_hv()
      under certain circumstances, and this is safe because (a) any vcpus
      that become runnable and are added to the runnable set by
      kvmppc_run_vcpu() have their vcpu->arch.trap == 0 and can't actually
      run in the guest (because the vcore state is VCORE_EXITING), and
      (b) for_each_runnable_thread is safe against addition or removal
      of vcpus from the runnable set.
      
      Therefore, in order to simplify things for following patches, let's
      drop the vcore lock in the for_each_runnable_thread loop, so
      kvmppc_handle_exit_hv() gets called without the vcore lock held.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      53655ddd
    • Paul Mackerras's avatar
      KVM: PPC: Book3S: Rework TM save/restore code and make it C-callable · 7854f754
      Paul Mackerras authored
      This adds a parameter to __kvmppc_save_tm and __kvmppc_restore_tm
      which allows the caller to indicate whether it wants the nonvolatile
      register state to be preserved across the call, as required by the C
      calling conventions.  This parameter being non-zero also causes the
      MSR bits that enable TM, FP, VMX and VSX to be preserved.  The
      condition register and DSCR are now always preserved.
      
      With this, kvmppc_save_tm_hv and kvmppc_restore_tm_hv can be called
      from C code provided the 3rd parameter is non-zero.  So that these
      functions can be called from modules, they now include code to set
      the TOC pointer (r2) on entry, as they can call other built-in C
      functions which will assume the TOC to have been set.
      
      Also, the fake suspend code in kvmppc_save_tm_hv is modified here to
      assume that treclaim in fake-suspend state does not modify any registers,
      which is the case on POWER9.  This enables the code to be simplified
      quite a bit.
      
      _kvmppc_save_tm_pr and _kvmppc_restore_tm_pr become much simpler with
      this change, since they now only need to save and restore TAR and pass
      1 for the 3rd argument to __kvmppc_{save,restore}_tm.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      7854f754
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Simplify real-mode interrupt handling · df709a29
      Paul Mackerras authored
      This streamlines the first part of the code that handles a hypervisor
      interrupt that occurred in the guest.  With this, all of the real-mode
      handling that occurs is done before the "guest_exit_cont" label; once
      we get to that label we are committed to exiting to host virtual mode.
      Thus the machine check and HMI real-mode handling is moved before that
      label.
      
      Also, the code to handle external interrupts is moved out of line, as
      is the code that calls kvmppc_realmode_hmi_handler().
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      df709a29
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Extract PMU save/restore operations as C-callable functions · 41f4e631
      Paul Mackerras authored
      This pulls out the assembler code that is responsible for saving and
      restoring the PMU state for the host and guest into separate functions
      so they can be used from an alternate entry path.  The calling
      convention is made compatible with C.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Reviewed-by: default avatarMadhavan Srinivasan <maddy@linux.vnet.ibm.com>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      41f4e631
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Move interrupt delivery on guest entry to C code · f7035ce9
      Paul Mackerras authored
      This is based on a patch by Suraj Jitindar Singh.
      
      This moves the code in book3s_hv_rmhandlers.S that generates an
      external, decrementer or privileged doorbell interrupt just before
      entering the guest to C code in book3s_hv_builtin.c.  This is to
      make future maintenance and modification easier.  The algorithm
      expressed in the C code is almost identical to the previous
      algorithm.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      f7035ce9
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Remove left-over code in XICS-on-XIVE emulation · 966eba93
      Paul Mackerras authored
      This removes code that clears the external interrupt pending bit in
      the pending_exceptions bitmap.  This is left over from an earlier
      iteration of the code where this bit was set when an escalation
      interrupt arrived in order to wake the vcpu from cede.  Currently
      we set the vcpu->arch.irq_pending flag instead for this purpose.
      Therefore there is no need to do anything with the pending_exceptions
      bitmap.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      966eba93
    • Paul Mackerras's avatar
      KVM: PPC: Book3S: Simplify external interrupt handling · d24ea8a7
      Paul Mackerras authored
      Currently we use two bits in the vcpu pending_exceptions bitmap to
      indicate that an external interrupt is pending for the guest, one
      for "one-shot" interrupts that are cleared when delivered, and one
      for interrupts that persist until cleared by an explicit action of
      the OS (e.g. an acknowledge to an interrupt controller).  The
      BOOK3S_IRQPRIO_EXTERNAL bit is used for one-shot interrupt requests
      and BOOK3S_IRQPRIO_EXTERNAL_LEVEL is used for persisting interrupts.
      
      In practice BOOK3S_IRQPRIO_EXTERNAL never gets used, because our
      Book3S platforms generally, and pseries in particular, expect
      external interrupt requests to persist until they are acknowledged
      at the interrupt controller.  That combined with the confusion
      introduced by having two bits for what is essentially the same thing
      makes it attractive to simplify things by only using one bit.  This
      patch does that.
      
      With this patch there is only BOOK3S_IRQPRIO_EXTERNAL, and by default
      it has the semantics of a persisting interrupt.  In order to avoid
      breaking the ABI, we introduce a new "external_oneshot" flag which
      preserves the behaviour of the KVM_INTERRUPT ioctl with the
      KVM_INTERRUPT_SET argument.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      d24ea8a7
    • Paul Mackerras's avatar
      powerpc: Turn off CPU_FTR_P9_TM_HV_ASSIST in non-hypervisor mode · e7b17d50
      Paul Mackerras authored
      When doing nested virtualization, it is only necessary to do the
      transactional memory hypervisor assist at level 0, that is, when
      we are in hypervisor mode.  Nested hypervisors can just use the TM
      facilities as architected.  Therefore we should clear the
      CPU_FTR_P9_TM_HV_ASSIST bit when we are not in hypervisor mode,
      along with the CPU_FTR_HVMODE bit.
      
      Doing this will not change anything at this stage because the only
      code that tests CPU_FTR_P9_TM_HV_ASSIST is in HV KVM, which currently
      can only be used when when CPU_FTR_HVMODE is set.
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      e7b17d50
    • Alexey Kardashevskiy's avatar
      KVM: PPC: Remove redundand permission bits removal · a3ac077b
      Alexey Kardashevskiy authored
      The kvmppc_gpa_to_ua() helper itself takes care of the permission
      bits in the TCE and yet every single caller removes them.
      
      This changes semantics of kvmppc_gpa_to_ua() so it takes TCEs
      (which are GPAs + TCE permission bits) to make the callers simpler.
      
      This should cause no behavioural change.
      Signed-off-by: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      a3ac077b
    • Alexey Kardashevskiy's avatar
      KVM: PPC: Propagate errors to the guest when failed instead of ignoring · 2691f0ff
      Alexey Kardashevskiy authored
      At the moment if the PUT_TCE{_INDIRECT} handlers fail to update
      the hardware tables, we print a warning once, clear the entry and
      continue. This is so as at the time the assumption was that if
      a VFIO device is hotplugged into the guest, and the userspace replays
      virtual DMA mappings (i.e. TCEs) to the hardware tables and if this fails,
      then there is nothing useful we can do about it.
      
      However the assumption is not valid as these handlers are not called for
      TCE replay (VFIO ioctl interface is used for that) and these handlers
      are for new TCEs.
      
      This returns an error to the guest if there is a request which cannot be
      processed. By now the only possible failure must be H_TOO_HARD.
      Signed-off-by: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      2691f0ff
    • Alexey Kardashevskiy's avatar
      KVM: PPC: Validate TCEs against preregistered memory page sizes · 42de7b9e
      Alexey Kardashevskiy authored
      The userspace can request an arbitrary supported page size for a DMA
      window and this works fine as long as the mapped memory is backed with
      the pages of the same or bigger size; if this is not the case,
      mm_iommu_ua_to_hpa{_rm}() fail and tables do not populated with
      dangerously incorrect TCEs.
      
      However since it is quite easy to misconfigure the KVM and we do not do
      reverts to all changes made to TCE tables if an error happens in a middle,
      we better do the acceptable page size validation before we even touch
      the tables.
      
      This enhances kvmppc_tce_validate() to check the hardware IOMMU page sizes
      against the preregistered memory page sizes.
      
      Since the new check uses real/virtual mode helpers, this renames
      kvmppc_tce_validate() to kvmppc_rm_tce_validate() to handle the real mode
      case and mirrors it for the virtual mode under the old name. The real
      mode handler is not used for the virtual mode as:
      1. it uses _lockless() list traversing primitives instead of RCU;
      2. realmode's mm_iommu_ua_to_hpa_rm() uses vmalloc_to_phys() which
      virtual mode does not have to use and since on POWER9+radix only virtual
      mode handlers actually work, we do not want to slow down that path even
      a bit.
      
      This removes EXPORT_SYMBOL_GPL(kvmppc_tce_validate) as the validators
      are static now.
      
      From now on the attempts on mapping IOMMU pages bigger than allowed
      will result in KVM exit.
      Signed-off-by: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      [mpe: Fix KVM_HV=n build]
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      42de7b9e
  2. 02 Oct, 2018 3 commits
  3. 11 Sep, 2018 2 commits
    • Nicholas Piggin's avatar
      KVM: PPC: Book3S HV: Don't use compound_order to determine host mapping size · 71d29f43
      Nicholas Piggin authored
      THP paths can defer splitting compound pages until after the actual
      remap and TLB flushes to split a huge PMD/PUD. This causes radix
      partition scope page table mappings to get out of synch with the host
      qemu page table mappings.
      
      This results in random memory corruption in the guest when running
      with THP. The easiest way to reproduce is use KVM balloon to free up
      a lot of memory in the guest and then shrink the balloon to give the
      memory back, while some work is being done in the guest.
      
      Cc: David Gibson <david@gibson.dropbear.id.au>
      Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
      Cc: kvm-ppc@vger.kernel.org
      Cc: linuxppc-dev@lists.ozlabs.org
      Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      71d29f43
    • Alexey Kardashevskiy's avatar
      KVM: PPC: Avoid marking DMA-mapped pages dirty in real mode · 425333bf
      Alexey Kardashevskiy authored
      At the moment the real mode handler of H_PUT_TCE calls iommu_tce_xchg_rm()
      which in turn reads the old TCE and if it was a valid entry, marks
      the physical page dirty if it was mapped for writing. Since it is in
      real mode, realmode_pfn_to_page() is used instead of pfn_to_page()
      to get the page struct. However SetPageDirty() itself reads the compound
      page head and returns a virtual address for the head page struct and
      setting dirty bit for that kills the system.
      
      This adds additional dirty bit tracking into the MM/IOMMU API for use
      in the real mode. Note that this does not change how VFIO and
      KVM (in virtual mode) set this bit. The KVM (real mode) changes include:
      - use the lowest bit of the cached host phys address to carry
      the dirty bit;
      - mark pages dirty when they are unpinned which happens when
      the preregistered memory is released which always happens in virtual
      mode;
      - add mm_iommu_ua_mark_dirty_rm() helper to set delayed dirty bit;
      - change iommu_tce_xchg_rm() to take the kvm struct for the mm to use
      in the new mm_iommu_ua_mark_dirty_rm() helper;
      - move iommu_tce_xchg_rm() to book3s_64_vio_hv.c (which is the only
      caller anyway) to reduce the real mode KVM and IOMMU knowledge
      across different subsystems.
      
      This removes realmode_pfn_to_page() as it is not used anymore.
      
      While we at it, remove some EXPORT_SYMBOL_GPL() as that code is for
      the real mode only and modules cannot call it anyway.
      Signed-off-by: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
      Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      425333bf
  4. 10 Sep, 2018 1 commit
  5. 09 Sep, 2018 2 commits
    • Linus Torvalds's avatar
      Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 9a568276
      Linus Torvalds authored
      Pull x86 fixes from Thomas Gleixner:
       "A set of fixes for x86:
      
         - Prevent multiplication result truncation on 32bit. Introduced with
           the early timestamp reworrk.
      
         - Ensure microcode revision storage to be consistent under all
           circumstances
      
         - Prevent write tearing of PTEs
      
         - Prevent confusion of user and kernel reegisters when dumping fatal
           signals verbosely
      
         - Make an error return value in a failure path of the vector
           allocation negative. Returning EINVAL might the caller assume
           success and causes further wreckage.
      
         - A trivial kernel doc warning fix"
      
      * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        x86/mm: Use WRITE_ONCE() when setting PTEs
        x86/apic/vector: Make error return value negative
        x86/process: Don't mix user/kernel regs in 64bit __show_regs()
        x86/tsc: Prevent result truncation on 32bit
        x86: Fix kernel-doc atomic.h warnings
        x86/microcode: Update the new microcode revision unconditionally
        x86/microcode: Make sure boot_cpu_data.microcode is up-to-date
      9a568276
    • Linus Torvalds's avatar
      Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 3567994a
      Linus Torvalds authored
      Pull timekeeping fixes from Thomas Gleixner:
       "Two fixes for timekeeping:
      
         - Revert to the previous kthread based update, which is unfortunately
           required due to lock ordering issues. The removal caused boot
           failures on old Core2 machines. Add a proper comment why the thread
           needs to stay to prevent accidental removal in the future.
      
         - Fix a silly typo in a function declaration"
      
      * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        clocksource: Revert "Remove kthread"
        timekeeping: Fix declaration of read_persistent_wall_and_boot_offset()
      3567994a