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Date: Sat, 12 May 2018 20:24:14 -0700 From: Wanpeng Li <kernellwp@...il.com> To: linux-kernel@...r.kernel.org, kvm@...r.kernel.org Cc: Paolo Bonzini <pbonzini@...hat.com>, Radim Krčmář <rkrcmar@...hat.com>, Junaid Shahid <junaids@...gle.com> Subject: [PATCH 2/2] KVM: X86: Fix loss of CR3_PCID_INVD bit when guest writes CR3 From: Wanpeng Li <wanpengli@...cent.com> SDM volume 3, section 4.10.4: * MOV to CR3. The behavior of the instruction depends on the value of CR4.PCIDE: — If CR4.PCIDE = 1 and bit 63 of the instruction’s source operand is 1, the instruction is not required to invalidate any TLB entries or entries in paging-structure caches. The CR3_PCID_INVD bit should not be removed if CR4.PCIDE = 1 when guest writes CR3, this patch fixes it. Cc: Paolo Bonzini <pbonzini@...hat.com> Cc: Radim Krčmář <rkrcmar@...hat.com> Cc: Junaid Shahid <junaids@...gle.com> Signed-off-by: Wanpeng Li <wanpengli@...cent.com> --- arch/x86/kvm/x86.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 9a90668..438f140 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -849,11 +849,13 @@ EXPORT_SYMBOL_GPL(kvm_set_cr4); int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) { + unsigned long cr3_check = cr3; + #ifdef CONFIG_X86_64 bool pcid_enabled = kvm_read_cr4_bits(vcpu, X86_CR4_PCIDE); if (pcid_enabled) - cr3 &= ~CR3_PCID_INVD; + cr3_check &= ~CR3_PCID_INVD; #endif if (cr3 == kvm_read_cr3(vcpu) && !pdptrs_changed(vcpu)) { @@ -863,7 +865,7 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) } if (is_long_mode(vcpu) && - (cr3 & rsvd_bits(cpuid_maxphyaddr(vcpu), 63))) + (cr3_check & rsvd_bits(cpuid_maxphyaddr(vcpu), 63))) return 1; else if (is_pae(vcpu) && is_paging(vcpu) && !load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3)) -- 2.7.4
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