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  1. 22 Sep, 2022 5 commits
    • Dr. David Alan Gilbert's avatar
      KVM: x86: Always enable legacy FP/SSE in allowed user XFEATURES · a1020a25
      Dr. David Alan Gilbert authored 
      Allow FP and SSE state to be saved and restored via KVM_{G,SET}_XSAVE on
XSAVE-capable hosts even if their bits are not exposed to the guest via
XCR0.

Failing to allow FP+SSE first showed up as a QEMU live migration failure,
where migrating a VM from a pre-XSAVE host, e.g. Nehalem, to an XSAVE
host failed due to KVM rejecting KVM_SET_XSAVE.  However, the bug also
causes problems even when migrating between XSAVE-capable hosts as
KVM_GET_SAVE won't set any bits in user_xfeatures if XSAVE isn't exposed
to the guest, i.e. KVM will fail to actually migrate FP+SSE.

Because KVM_{G,S}ET_XSAVE are designed to allowing migrating between
hosts with and without XSAVE, KVM_GET_XSAVE on a non-XSAVE (by way of
fpu_copy_guest_fpstate_to_uabi()) always sets the FP+SSE bits in the
header so that KVM_SET_XSAVE will work even if the new host supports
XSAVE.

Fixes: ad856280 ("x86/kvm/fpu: Limit guest user_xfeatures to supported bits of XCR0")
bz: https://bugzilla.redhat.com/show_bug.cgi?id=2079311
Cc: stable@vger.kernel.org
Cc: Leonardo Bras <leobras@redhat.com>
Signed-off-by: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
[sean: add comment, massage changelog]
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20220824033057.3576315-3-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      a1020a25
    • Sean Christopherson's avatar
      KVM: x86: Reinstate kvm_vcpu_arch.guest_supported_xcr0 · ee519b3a
      Sean Christopherson authored 
      Reinstate the per-vCPU guest_supported_xcr0 by partially reverting
commit 988896bb; the implicit assessment that guest_supported_xcr0 is
always the same as guest_fpu.fpstate->user_xfeatures was incorrect.

kvm_vcpu_after_set_cpuid() isn't the only place that sets user_xfeatures,
as user_xfeatures is set to fpu_user_cfg.default_features when guest_fpu
is allocated via fpu_alloc_guest_fpstate() => __fpstate_reset().
guest_supported_xcr0 on the other hand is zero-allocated.  If userspace
never invokes KVM_SET_CPUID2, supported XCR0 will be '0', whereas the
allowed user XFEATURES will be non-zero.

Practically speaking, the edge case likely doesn't matter as no sane
userspace will live migrate a VM without ever doing KVM_SET_CPUID2. The
primary motivation is to prepare for KVM intentionally and explicitly
setting bits in user_xfeatures that are not set in guest_supported_xcr0.

Because KVM_{G,S}ET_XSAVE can be used to svae/restore FP+SSE state even
if the host doesn't support XSAVE, KVM needs to set the FP+SSE bits in
user_xfeatures even if they're not allowed in XCR0, e.g. because XCR0
isn't exposed to the guest.  At that point, the simplest fix is to track
the two things separately (allowed save/restore vs. allowed XCR0).

Fixes: 988896bb ("x86/kvm/fpu: Remove kvm_vcpu_arch.guest_supported_xcr0")
Cc: stable@vger.kernel.org
Cc: Leonardo Bras <leobras@redhat.com>
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20220824033057.3576315-2-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      ee519b3a
    • Miaohe Lin's avatar
      KVM: x86/mmu: add missing update to max_mmu_rmap_size · 604f5332
      Miaohe Lin authored 
      The update to statistic max_mmu_rmap_size is unintentionally removed by
commit 4293ddb7 ("KVM: x86/mmu: Remove redundant spte present check
in mmu_set_spte"). Add missing update to it or max_mmu_rmap_size will
always be nonsensical 0.

Fixes: 4293ddb7 ("KVM: x86/mmu: Remove redundant spte present check in mmu_set_spte")
Signed-off-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Message-Id: <20220907080657.42898-1-linmiaohe@huawei.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      604f5332
    • Jinrong Liang's avatar
      selftests: kvm: Fix a compile error in selftests/kvm/rseq_test.c · 561cafeb
      Jinrong Liang authored 
      The following warning appears when executing:
	make -C tools/testing/selftests/kvm

rseq_test.c: In function ‘main’:
rseq_test.c:237:33: warning: implicit declaration of function ‘gettid’; did you mean ‘getgid’? [-Wimplicit-function-declaration]
          (void *)(unsigned long)gettid());
                                 ^~~~~~
                                 getgid
/usr/bin/ld: /tmp/ccr5mMko.o: in function `main':
../kvm/tools/testing/selftests/kvm/rseq_test.c:237: undefined reference to `gettid'
collect2: error: ld returned 1 exit status
make: *** [../lib.mk:173: ../kvm/tools/testing/selftests/kvm/rseq_test] Error 1

Use the more compatible syscall(SYS_gettid) instead of gettid() to fix it.
More subsequent reuse may cause it to be wrapped in a lib file.
Signed-off-by: default avatarJinrong Liang <cloudliang@tencent.com>
Message-Id: <20220802071240.84626-1-cloudliang@tencent.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      561cafeb
    • Paolo Bonzini's avatar
      Merge tag 'kvmarm-fixes-6.0-2' of... · b4ac28a3
      Paolo Bonzini authored 
      Merge tag 'kvmarm-fixes-6.0-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 fixes for 6.0, take #2

- Fix kmemleak usage in Protected KVM (again)
      b4ac28a3
  3. 19 Sep, 2022 1 commit
  5. 01 Sep, 2022 6 commits
  7. 29 Aug, 2022 1 commit
  9. 28 Aug, 2022 25 commits
  11. 27 Aug, 2022 2 commits
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