- 17 Nov, 2022 31 commits
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David Matlack authored
Add a selftest to exercise the KVM_CAP_EXIT_ON_EMULATION_FAILURE capability. This capability is also exercised through smaller_maxphyaddr_emulation_test, but that test requires allow_smaller_maxphyaddr=Y, which is off by default on Intel when ept=Y and unconditionally disabled on AMD when npt=Y. This new test ensures that KVM_CAP_EXIT_ON_EMULATION_FAILURE is exercised independent of allow_smaller_maxphyaddr. Signed-off-by:
David Matlack <dmatlack@google.com> Link: https://lore.kernel.org/r/20221102184654.282799-11-dmatlack@google.comSigned-off-by:
Sean Christopherson <seanjc@google.com>
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David Matlack authored
Change smaller_maxphyaddr_emulation_test to expect a #PF(RSVD), rather than an emulation failure, when TDP is disabled. KVM only needs to emulate instructions to emulate a smaller guest.MAXPHYADDR when TDP is enabled. Fixes: 39bbcc3a ("selftests: kvm: Allows userspace to handle emulation errors.") Signed-off-by:
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Sean Christopherson authored
Provide the error code on a fault in KVM_ASM_SAFE(), e.g. to allow tests to assert that #PF generates the correct error code without needing to manually install a #PF handler. Use r10 as the scratch register for the error code, as it's already clobbered by the asm blob (loaded with the RIP of the to-be-executed instruction). Deliberately load the output "error_code" even in the non-faulting path so that error_code is always initialized with deterministic data (the aforementioned RIP), i.e to ensure a selftest won't end up with uninitialized consumption regardless of how KVM_ASM_SAFE() is used. Don't clear r10 in the non-faulting case and instead load error code with the RIP (see above). The error code is valid if and only if an exception occurs, and '0' isn't necessarily a better "invalid" value, e.g. '0' could result in false passes for a buggy test. Signed-off-by:
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Sean Christopherson authored
Clear R9 in the non-faulting path of KVM_ASM_SAFE() and fall through to to a common load of "vector" to effectively load "vector" with '0' to reduce the code footprint of the asm blob, to reduce the runtime overhead of the non-faulting path (when "vector" is stored in a register), and so that additional output constraints that are valid if and only if a fault occur are loaded even in the non-faulting case. A future patch will add a 64-bit output for the error code, and if its output is not explicitly loaded with _something_, the user of the asm blob can end up technically consuming uninitialized data. Using a common path to load the output constraints will allow using an existing scratch register, e.g. r10, to hold the error code in the faulting path, while also guaranteeing the error code is initialized with deterministic data in the non-faulting patch (r10 is loaded with the RIP of to-be-executed instruction). Consuming the error code when a fault doesn't occur would obviously be a test bug, but there's no guarantee the compiler will detect uninitialized consumption. And conversely, it's theoretically possible that the compiler might throw a false positive on uninitialized data, e.g. if the compiler can't determine that the non-faulting path won't touch the error code. Alternatively, the error code could be explicitly loaded in the non-faulting path, but loading a 64-bit memory|register output operand with an explicitl value requires a sign-extended "MOV imm32, r/m64", which isn't exactly straightforward and has a largish code footprint. And loading the error code with what is effectively garbage (from a scratch register) avoids having to choose an arbitrary value for the non-faulting case. Opportunistically remove a rogue asterisk in the block comment. Signed-off-by:
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David Matlack authored
Copy KVM's macros for page fault error masks into processor.h so they can be used in selftests. Signed-off-by:
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David Matlack authored
Use the preferred BIT() and BIT_ULL() to construct the PFERR masks rather than open-coding the bit shifting. No functional change intended. Signed-off-by:
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David Matlack authored
Move the flds instruction emulation failure handling code to a header so it can be re-used in an upcoming test. No functional change intended. Signed-off-by:
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David Matlack authored
Delete a bunch of code related to ucall handling from smaller_maxphyaddr_emulation_test. The only thing smaller_maxphyaddr_emulation_test needs to check is that the vCPU exits with UCALL_DONE after the second vcpu_run(). Signed-off-by:
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David Matlack authored
Hard-code the flds instruction and assert the exact instruction bytes are present in run->emulation_failure. The test already requires the instruction bytes to be present because that's the only way the test will advance the RIP past the flds and get to GUEST_DONE(). Note that KVM does not necessarily return exactly 2 bytes in run->emulation_failure since it may not know the exact instruction length in all cases. So just assert that run->emulation_failure.insn_size is at least 2. Signed-off-by:
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David Matlack authored
Rename emulator_error_test to smaller_maxphyaddr_emulation_test and update the comment at the top of the file to document that this is explicitly a test to validate that KVM emulates instructions in response to an EPT violation when emulating a smaller MAXPHYADDR. Signed-off-by:
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Gautam Menghani authored
In xapic_state_test's test_icr(), explicitly skip iterations that would match vcpu->id instead of assuming vcpu->id is '0', so that IPIs are are correctly sent to non-existent vCPUs. Suggested-by:
Gautam Menghani <gautammenghani201@gmail.com> Link: https://lore.kernel.org/r/20221017175819.12672-1-gautammenghani201@gmail.com [sean: massage shortlog and changelog] Signed-off-by:
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Vishal Annapurve authored
Add arch specific API kvm_arch_vm_post_create to perform any required setup after VM creation. Suggested-by:
Andrew Jones <andrew.jones@linux.dev> Reviewed-by:
Peter Gonda <pgonda@google.com> Signed-off-by:
Vishal Annapurve <vannapurve@google.com> Link: https://lore.kernel.org/r/20221115213845.3348210-4-vannapurve@google.com [sean: place x86's implementation by vm_arch_vcpu_add()] Signed-off-by:
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Vishal Annapurve authored
Introduce arch specific API: kvm_selftest_arch_init to allow each arch to handle initialization before running any selftest logic. Suggested-by:
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Vishal Annapurve authored
Consolidate common startup logic in one place by implementing a single setup function with __attribute((constructor)) for all selftests within kvm_util.c. This allows moving logic like: /* Tell stdout not to buffer its content */ setbuf(stdout, NULL); to a single file for all selftests. This will also allow any required setup at entry in future to be done in common main function. Link: https://lore.kernel.org/lkml/Ywa9T+jKUpaHLu%2Fl@google.comSuggested-by: -
Sean Christopherson authored
Play nice with huge pages when getting PTEs and translating GVAs to GPAs, there's no reason to disallow using huge pages in selftests. Use PG_LEVEL_NONE to indicate that the caller doesn't care about the mapping level and just wants to get the pte+level. Signed-off-by:
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Sean Christopherson authored
Use vm_get_page_table_entry() in addr_arch_gva2gpa() to get the leaf PTE instead of manually walking page tables. Signed-off-by:
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Sean Christopherson authored
Use virt_get_pte() in vm_get_page_table_entry() instead of open coding equivalent code. Signed-off-by:
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Sean Christopherson authored
Verify the parent PTE is PRESENT when getting a child via virt_get_pte() so that the helper can be used for getting PTEs/GPAs without losing sanity checks that the walker isn't wandering into the weeds. Signed-off-by:
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Sean Christopherson authored
Remove the pointless shift from GPA=>GFN and immediately back to GFN=>GPA when creating guest page tables. Ignore the other walkers that have a similar pattern for the moment, they will be converted to use virt_get_pte() in the near future. No functional change intended. Signed-off-by:
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Sean Christopherson authored
Drop the reserved bit checks from the helper to retrieve a PTE, there's very little value in sanity checking the constructed page tables as any will quickly be noticed in the form of an unexpected #PF. The checks also place unnecessary restrictions on the usage of the helpers, e.g. if a test _wanted_ to set reserved bits for whatever reason. Removing the NX check in particular allows for the removal of the @vcpu param, which will in turn allow the helper to be reused nearly verbatim for addr_gva2gpa(). Signed-off-by:
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Sean Christopherson authored
Drop vm_{g,s}et_page_table_entry() and instead expose the "inner" helper (was _vm_get_page_table_entry()) that returns a _pointer_ to the PTE, i.e. let tests directly modify PTEs instead of bouncing through helpers that just make life difficult. Opportunsitically use BIT_ULL() in emulator_error_test, and use the MAXPHYADDR define to set the "rogue" GPA bit instead of open coding the same value. No functional change intended. Signed-off-by: -
Colin Ian King authored
There is a spelling mistake in an assert message. Fix it. Signed-off-by:
Colin Ian King <colin.i.king@gmail.com> Reviewed-by:
Jim Mattson <jmattson@google.com> Link: https://lore.kernel.org/r/20220928213458.64089-1-colin.i.king@gmail.com [sean: fix an ironic typo in the changelog] Signed-off-by:
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Peter Gonda authored
To play nice with guests whose stack memory is encrypted, e.g. AMD SEV, introduce a new "ucall pool" implementation that passes the ucall struct via dedicated memory (which can be mapped shared, a.k.a. as plain text). Because not all architectures have access to the vCPU index in the guest, use a bitmap with atomic accesses to track which entries in the pool are free/used. A list+lock could also work in theory, but synchronizing the individual pointers to the guest would be a mess. Note, there's no need to rewalk the bitmap to ensure success. If all vCPUs are simply allocating, success is guaranteed because there are enough entries for all vCPUs. If one or more vCPUs are freeing and then reallocating, success is guaranteed because vCPUs _always_ walk the bitmap from 0=>N; if vCPU frees an entry and then wins a race to re-allocate, then either it will consume the entry it just freed (bit is the first free bit), or the losing vCPU is guaranteed to see the freed bit (winner consumes an earlier bit, which the loser hasn't yet visited). Reviewed-by:
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Sean Christopherson authored
Drop ucall_uninit() and ucall_arch_uninit() now that ARM doesn't modify the host's copy of ucall_exit_mmio_addr, i.e. now that there's no need to reset the pointer before potentially creating a new VM. The few calls to ucall_uninit() are all immediately followed by kvm_vm_free(), and that is likely always going to hold true, i.e. it's extremely unlikely a test will want to effectively disable ucall in the middle of a test. Reviewed-by:
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Sean Christopherson authored
Fix a mostly-theoretical bug where ARM's ucall MMIO setup could result in different VMs stomping on each other by cloberring the global pointer. Fix the most obvious issue by saving the MMIO gpa into the VM. A more subtle bug is that creating VMs in parallel (on multiple tasks) could result in a VM using the wrong address. Synchronizing a global to a guest effectively snapshots the value on a per-VM basis, i.e. the "global" is already prepped to work with multiple VMs, but setting the global in the host is not thread-safe. To fix that bug, add write_guest_global() to allow stuffing a VM's copy of a "global" without modifying the host value. Reviewed-by:
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Peter Gonda authored
Add x86 and generic implementations of atomic_test_and_set_bit() to allow KVM selftests to atomically manage bitmaps. Note, the generic version is taken from arch_test_and_set_bit() as of commit 415d8324 ("locking/atomic: Make test_and_*_bit() ordered on failure"). Signed-off-by:
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Sean Christopherson authored
Do init_ucall() automatically during VM creation to kill two (three?) birds with one stone. First, initializing ucall immediately after VM creations allows forcing aarch64's MMIO ucall address to immediately follow memslot0. This is still somewhat fragile as tests could clobber the MMIO address with a new memslot, but it's safe-ish since tests have to be conversative when accounting for memslot0. And this can be hardened in the future by creating a read-only memslot for the MMIO page (KVM ARM exits with MMIO if the guest writes to a read-only memslot). Add a TODO to document that selftests can and should use a memslot for the ucall MMIO (doing so requires yet more rework because tests assumes thay can use all memslots except memslot0). Second, initializing ucall for all VMs prepares for making ucall initialization meaningful on all architectures. aarch64 is currently the only arch that needs to do any setup, but that will change in the future by switching to a pool-based implementation (instead of the current stack-based approach). Lastly, defining the ucall MMIO address from common code will simplify switching all architectures (except s390) to a common MMIO-based ucall implementation (if there's ever sufficient motivation to do so). Cc: Oliver Upton <oliver.upton@linux.dev> Reviewed-by:
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Sean Christopherson authored
Consolidate the actual copying of a ucall struct from guest=>host into the common get_ucall(). Return a host virtual address instead of a guest virtual address even though the addr_gva2hva() part could be moved to get_ucall() too. Conceptually, get_ucall() is invoked from the host and should return a host virtual address (and returning NULL for "nothing to see here" is far superior to returning 0). Use pointer shenanigans instead of an unnecessary bounce buffer when the caller of get_ucall() provides a valid pointer. Reviewed-by:
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Sean Christopherson authored
Make ucall() a common helper that populates struct ucall, and only calls into arch code to make the actually call out to userspace. Rename all arch-specific helpers to make it clear they're arch-specific, and to avoid collisions with common helpers (one more on its way...) Add WRITE_ONCE() to stores in ucall() code (as already done to aarch64 code in commit 9e2f6498 ("selftests: KVM: Handle compiler optimizations in ucall")) to prevent clang optimizations breaking ucalls. Cc: Colton Lewis <coltonlewis@google.com> Reviewed-by:
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Sean Christopherson authored
Automatically disable single-step when the guest reaches the end of the verified section instead of using an explicit ucall() to ask userspace to disable single-step. An upcoming change to implement a pool-based scheme for ucall() will add an atomic operation (bit test and set) in the guest ucall code, and if the compiler generate "old school" atomics, e.g. 40e57c: c85f7c20 ldxr x0, [x1] 40e580: aa100011 orr x17, x0, x16 40e584: c80ffc31 stlxr w15, x17, [x1] 40e588: 35ffffaf cbnz w15, 40e57c <__aarch64_ldset8_sync+0x1c> the guest will hang as the local exclusive monitor is reset by eret, i.e. the stlxr will always fail due to the debug exception taken to EL2. Link: https://lore.kernel.org/all/20221006003409.649993-8-seanjc@google.com Cc: Oliver Upton <oliver.upton@linux.dev> Cc: Marc Zyngier <maz@kernel.org> Signed-off-by:
Oliver Upton <oliver.upton@linux.dev>
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Sean Christopherson authored
Disable single-step by setting debug.control to KVM_GUESTDBG_ENABLE, not to SINGLE_STEP_DISABLE. The latter is an arbitrary test enum that just happens to have the same value as KVM_GUESTDBG_ENABLE, and so effectively disables single-step debug. No functional change intended. Cc: Reiji Watanabe <reijiw@google.com> Fixes: b18e4d4a ("KVM: arm64: selftests: Add a test case for KVM_GUESTDBG_SINGLESTEP") Signed-off-by:
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- 16 Nov, 2022 9 commits
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David Matlack authored
Replace the perf_test_ prefix on symbol names with memstress_ to match the new file name. "memstress" better describes the functionality proveded by this library, which is to provide functionality for creating and running a VM that stresses VM memory by reading and writing to guest memory on all vCPUs in parallel. "memstress" also contains the same number of chracters as "perf_test", making it a drop-in replacement in symbols, e.g. function names, without impacting line lengths. Also the lack of underscore between "mem" and "stress" makes it clear "memstress" is a noun. Signed-off-by:
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David Matlack authored
Rename the local variables "pta" (which is short for perf_test_args) for args. "pta" is not an obvious acronym and using "args" mirrors "vcpu_args". Suggested-by:
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David Matlack authored
Rename the perf_test_util.[ch] files to memstress.[ch]. Symbols are renamed in the following commit to reduce the amount of churn here in hopes of playiing nice with git's file rename detection. The name "memstress" was chosen to better describe the functionality proveded by this library, which is to create and run a VM that reads/writes to guest memory on all vCPUs in parallel. "memstress" also contains the same number of chracters as "perf_test", making it a drop-in replacement in symbols, e.g. function names, without impacting line lengths. Also the lack of underscore between "mem" and "stress" makes it clear "memstress" is a noun. Signed-off-by:
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Colton Lewis authored
Create the ability to randomize page access order with the -a argument. This includes the possibility that the same pages may be hit multiple times during an iteration or not at all. Population has random access as false to ensure all pages will be touched by population and avoid page faults in late dirty memory that would pollute the test results. Signed-off-by:
Colton Lewis <coltonlewis@google.com> Reviewed-by:
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Colton Lewis authored
Randomize which pages are written vs read using the random number generator. Change the variable wr_fract and associated function calls to write_percent that now operates as a percentage from 0 to 100 where X means each page has an X% chance of being written. Change the -f argument to -w to reflect the new variable semantics. Keep the same default of 100% writes. Population always uses 100% writes to ensure all memory is actually populated and not just mapped to the zero page. The prevents expensive copy-on-write faults from occurring during the dirty memory iterations below, which would pollute the performance results. Each vCPU calculates its own random seed by adding its index to the seed provided. Signed-off-by:
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Colton Lewis authored
Create a -r argument to specify a random seed. If no argument is provided, the seed defaults to 1. The random seed is set with perf_test_set_random_seed() and must be set before guest_code runs to apply. Signed-off-by:
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Colton Lewis authored
Implement random number generator for guest code to randomize parts of the test, making it less predictable and a more accurate reflection of reality. The random number generator chosen is the Park-Miller Linear Congruential Generator, a fancy name for a basic and well-understood random number generator entirely sufficient for this purpose. Signed-off-by:
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Vipin Sharma authored
Add a command line option, -c, to pin vCPUs to physical CPUs (pCPUs), i.e. to force vCPUs to run on specific pCPUs. Requirement to implement this feature came in discussion on the patch "Make page tables for eager page splitting NUMA aware" https://lore.kernel.org/lkml/YuhPT2drgqL+osLl@google.com/ This feature is useful as it provides a way to analyze performance based on the vCPUs and dirty log worker locations, like on the different NUMA nodes or on the same NUMA nodes. To keep things simple, implementation is intentionally very limited, either all of the vCPUs will be pinned followed by an optional main thread or nothing will be pinned. Signed-off-by:
Vipin Sharma <vipinsh@google.com> Suggested-by:
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Vipin Sharma authored
Many KVM selftests take command line arguments which are supposed to be positive (>0) or non-negative (>=0). Some tests do these validation and some missed adding the check. Add atoi_positive() and atoi_non_negative() to validate inputs in selftests before proceeding to use those values. Signed-off-by:
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