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| author | Paolo Bonzini <pbonzini@redhat.com> | 2015-07-10 13:32:13 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2015-07-23 08:30:27 +0200 |
| commit | 5492830370171b6a4ede8a3bfba687a8d0f25fa5 (patch) | |
| tree | 44d7c401f31b3256be49f7f8db277b18506ce2d5 /arch/x86/kvm/svm.c | |
| parent | 5f3d45e7f2827f48e60eb821efd909713b43ac63 (diff) | |
| download | linux-5492830370171b6a4ede8a3bfba687a8d0f25fa5.tar.bz2 | |
KVM: svm: handle KVM_X86_QUIRK_CD_NW_CLEARED in svm_get_mt_mask
We can disable CD unconditionally when there is no assigned device.
KVM now forces guest PAT to all-writeback in that case, so it makes
sense to also force CR0.CD=0.
When there are assigned devices, emulate cache-disabled operation
through the page tables. This behavior is consistent with VMX
microcode, where CD/NW are not touched by vmentry/vmexit. However,
keep this dependent on the quirk because OVMF enables the caches
too late.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/svm.c')
| -rw-r--r-- | arch/x86/kvm/svm.c | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 8e0c0844c6b9..d1a114d8d22b 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1173,6 +1173,10 @@ static u64 svm_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) if (!is_mmio && !kvm_arch_has_assigned_device(vcpu->kvm)) return 0; + if (!kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_CD_NW_CLEARED) && + kvm_read_cr0(vcpu) & X86_CR0_CD) + return _PAGE_NOCACHE; + mtrr = kvm_mtrr_get_guest_memory_type(vcpu, gfn); return mtrr2protval[mtrr]; } @@ -1667,13 +1671,10 @@ static void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) if (!vcpu->fpu_active) cr0 |= X86_CR0_TS; - /* - * re-enable caching here because the QEMU bios - * does not do it - this results in some delay at - * reboot - */ - if (kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_CD_NW_CLEARED)) - cr0 &= ~(X86_CR0_CD | X86_CR0_NW); + + /* These are emulated via page tables. */ + cr0 &= ~(X86_CR0_CD | X86_CR0_NW); + svm->vmcb->save.cr0 = cr0; mark_dirty(svm->vmcb, VMCB_CR); update_cr0_intercept(svm); |