From bca06b85fcaf866602e328b3bcd86f74180eca14 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 24 Feb 2022 19:19:16 +0000 Subject: [PATCH] Revert "KVM: VMX: Save HOST_CR3 in vmx_set_host_fs_gs()" Undo a nested VMX fix as a step toward reverting the commit it fixed, 15ad9762d69f ("KVM: VMX: Save HOST_CR3 in vmx_prepare_switch_to_guest()"), as the underlying premise that "host CR3 in the vcpu thread can only be changed when scheduling" is wrong. This reverts commit a9f2705ec84449e3b8d70c804766f8e97e23080d. Signed-off-by: Sean Christopherson Message-Id: <20220224191917.3508476-2-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/nested.c | 3 +-- arch/x86/kvm/vmx/vmx.c | 20 +++++++++++--------- arch/x86/kvm/vmx/vmx.h | 5 ++--- 3 files changed, 14 insertions(+), 14 deletions(-) diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index ba34e94..c12f9500 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -246,8 +246,7 @@ static void vmx_sync_vmcs_host_state(struct vcpu_vmx *vmx, src = &prev->host_state; dest = &vmx->loaded_vmcs->host_state; - vmx_set_vmcs_host_state(dest, src->cr3, src->fs_sel, src->gs_sel, - src->fs_base, src->gs_base); + vmx_set_host_fs_gs(dest, src->fs_sel, src->gs_sel, src->fs_base, src->gs_base); dest->ldt_sel = src->ldt_sel; #ifdef CONFIG_X86_64 dest->ds_sel = src->ds_sel; diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index efda5e4..beb68cd 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1080,14 +1080,9 @@ static void pt_guest_exit(struct vcpu_vmx *vmx) wrmsrl(MSR_IA32_RTIT_CTL, vmx->pt_desc.host.ctl); } -void vmx_set_vmcs_host_state(struct vmcs_host_state *host, unsigned long cr3, - u16 fs_sel, u16 gs_sel, - unsigned long fs_base, unsigned long gs_base) +void vmx_set_host_fs_gs(struct vmcs_host_state *host, u16 fs_sel, u16 gs_sel, + unsigned long fs_base, unsigned long gs_base) { - if (unlikely(cr3 != host->cr3)) { - vmcs_writel(HOST_CR3, cr3); - host->cr3 = cr3; - } if (unlikely(fs_sel != host->fs_sel)) { if (!(fs_sel & 7)) vmcs_write16(HOST_FS_SELECTOR, fs_sel); @@ -1119,6 +1114,7 @@ void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu) #ifdef CONFIG_X86_64 int cpu = raw_smp_processor_id(); #endif + unsigned long cr3; unsigned long fs_base, gs_base; u16 fs_sel, gs_sel; int i; @@ -1182,8 +1178,14 @@ void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu) gs_base = segment_base(gs_sel); #endif - vmx_set_vmcs_host_state(host_state, __get_current_cr3_fast(), - fs_sel, gs_sel, fs_base, gs_base); + vmx_set_host_fs_gs(host_state, fs_sel, gs_sel, fs_base, gs_base); + + /* Host CR3 including its PCID is stable when guest state is loaded. */ + cr3 = __get_current_cr3_fast(); + if (unlikely(cr3 != host_state->cr3)) { + vmcs_writel(HOST_CR3, cr3); + host_state->cr3 = cr3; + } vmx->guest_state_loaded = true; } diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index 7f2c82e..9c6bfcd 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -374,9 +374,8 @@ int allocate_vpid(void); void free_vpid(int vpid); void vmx_set_constant_host_state(struct vcpu_vmx *vmx); void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu); -void vmx_set_vmcs_host_state(struct vmcs_host_state *host, unsigned long cr3, - u16 fs_sel, u16 gs_sel, - unsigned long fs_base, unsigned long gs_base); +void vmx_set_host_fs_gs(struct vmcs_host_state *host, u16 fs_sel, u16 gs_sel, + unsigned long fs_base, unsigned long gs_base); int vmx_get_cpl(struct kvm_vcpu *vcpu); bool vmx_emulation_required(struct kvm_vcpu *vcpu); unsigned long vmx_get_rflags(struct kvm_vcpu *vcpu); -- 2.7.4