Replace a KVM_REQ_MMU_RELOAD request with a direct kvm_mmu_unload() call when the guest's CR4.PCIDE changes. This will allow tweaking the logic of KVM_REQ_MMU_RELOAD to free only obsolete/invalid roots, which is the historical intent of KVM_REQ_MMU_RELOAD. The recent PCIDE behavior is the only user of KVM_REQ_MMU_RELOAD that doesn't mark affected roots as obsolete, needs to unconditionally unload the entire MMU, _and_ affects only the current vCPU. Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> --- arch/x86/kvm/x86.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 1aaf37e1bd0f..ca1f0350a868 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1045,19 +1045,18 @@ void kvm_post_set_cr4(struct kvm_vcpu *vcpu, unsigned long old_cr4, unsigned lon * If CR4.PCIDE is changed 0 -> 1, there is no need to flush the TLB * according to the SDM; however, stale prev_roots could be reused * incorrectly in the future after a MOV to CR3 with NOFLUSH=1, so we - * free them all. KVM_REQ_MMU_RELOAD is fit for the both cases; it - * is slow, but changing CR4.PCIDE is a rare case. + * free them all. kvm_mmu_unload() is fit for the both cases; it is + * slow, but changing CR4.PCIDE is a rare case. * * If CR4.PGE is changed, the guest TLB must be flushed. * - * Note: resetting MMU is a superset of KVM_REQ_MMU_RELOAD and - * KVM_REQ_MMU_RELOAD is a superset of KVM_REQ_TLB_FLUSH_GUEST, hence - * the usage of "else if". + * Note: resetting MMU is a superset of unloading an MMU, and unloading + * an MMU is a superset of KVM_REQ_TLB_FLUSH_GUEST, hence the "else if". */ if ((cr4 ^ old_cr4) & KVM_MMU_CR4_ROLE_BITS) kvm_mmu_reset_context(vcpu); else if ((cr4 ^ old_cr4) & X86_CR4_PCIDE) - kvm_make_request(KVM_REQ_MMU_RELOAD, vcpu); + kvm_mmu_unload(vcpu); else if ((cr4 ^ old_cr4) & X86_CR4_PGE) kvm_make_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu); } -- 2.34.1.400.ga245620fadb-goog
