diff mbox series

[v5,1/3] KVM: nVMX: Sync L2 guest CET states between L1/L2

Message ID 20210409064345.31497-2-weijiang.yang@intel.com (mailing list archive)
State New, archived
Headers show
Series CET fix patches for nested guest | expand

Commit Message

Yang Weijiang April 9, 2021, 6:43 a.m. UTC
These fields are rarely updated by L1 QEMU/KVM, sync them when L1 is trying to
read/write them and after they're changed. If CET guest entry-load bit is not
set by L1 guest, migrate them to L2 manaully.

Opportunistically remove one blank line in previous patch.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
---
 arch/x86/kvm/cpuid.c      |  1 -
 arch/x86/kvm/vmx/nested.c | 30 ++++++++++++++++++++++++++++++
 arch/x86/kvm/vmx/vmx.h    |  3 +++
 3 files changed, 33 insertions(+), 1 deletion(-)

Comments

Sean Christopherson April 20, 2021, 5:35 p.m. UTC | #1
On Fri, Apr 09, 2021, Yang Weijiang wrote:
> These fields are rarely updated by L1 QEMU/KVM, sync them when L1 is trying to
> read/write them and after they're changed. If CET guest entry-load bit is not
> set by L1 guest, migrate them to L2 manaully.
> 
> Opportunistically remove one blank line in previous patch.
> 
> Suggested-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
> ---
>  arch/x86/kvm/cpuid.c      |  1 -
>  arch/x86/kvm/vmx/nested.c | 30 ++++++++++++++++++++++++++++++
>  arch/x86/kvm/vmx/vmx.h    |  3 +++
>  3 files changed, 33 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index d191de769093..8692f53b8cd0 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -143,7 +143,6 @@ void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
>  		}
>  		vcpu->arch.guest_supported_xss =
>  			(((u64)best->edx << 32) | best->ecx) & supported_xss;
> -
>  	} else {
>  		vcpu->arch.guest_supported_xss = 0;
>  	}
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 9728efd529a1..87beb1c034e1 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -2516,6 +2516,13 @@ static void prepare_vmcs02_rare(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
>  	vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, vmx->msr_autoload.guest.nr);
>  
>  	set_cr4_guest_host_mask(vmx);
> +
> +	if (kvm_cet_supported() && vmx->nested.nested_run_pending &&
> +	    (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_CET_STATE)) {
> +		vmcs_writel(GUEST_SSP, vmcs12->guest_ssp);
> +		vmcs_writel(GUEST_S_CET, vmcs12->guest_s_cet);
> +		vmcs_writel(GUEST_INTR_SSP_TABLE, vmcs12->guest_ssp_tbl);
> +	}
>  }
>  
>  /*
> @@ -2556,6 +2563,15 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
>  	if (kvm_mpx_supported() && (!vmx->nested.nested_run_pending ||
>  	    !(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_BNDCFGS)))
>  		vmcs_write64(GUEST_BNDCFGS, vmx->nested.vmcs01_guest_bndcfgs);
> +
> +	if (kvm_cet_supported() && (!vmx->nested.nested_run_pending ||
> +	    !(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_CET_STATE))) {
> +		vmcs_writel(GUEST_SSP, vmx->nested.vmcs01_guest_ssp);
> +		vmcs_writel(GUEST_S_CET, vmx->nested.vmcs01_guest_s_cet);
> +		vmcs_writel(GUEST_INTR_SSP_TABLE,
> +			    vmx->nested.vmcs01_guest_ssp_tbl);
> +	}
> +
>  	vmx_set_rflags(vcpu, vmcs12->guest_rflags);
>  
>  	/* EXCEPTION_BITMAP and CR0_GUEST_HOST_MASK should basically be the
> @@ -3375,6 +3391,11 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
>  	if (kvm_mpx_supported() &&
>  		!(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_BNDCFGS))
>  		vmx->nested.vmcs01_guest_bndcfgs = vmcs_read64(GUEST_BNDCFGS);
> +	if (kvm_cet_supported() && !vmx->nested.nested_run_pending) {

This needs to be:

	if (kvm_cet_supported() && (!vmx->nested.nested_run_pending ||
	    !(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_CET_STATE)))

otherwise the vmcs01_* members will be stale when emulating VM-Enter with
vcmc12.vm_entry_controls.LOAD_CET_STATE=0.

> +		vmx->nested.vmcs01_guest_ssp = vmcs_readl(GUEST_SSP);
> +		vmx->nested.vmcs01_guest_s_cet = vmcs_readl(GUEST_S_CET);
> +		vmx->nested.vmcs01_guest_ssp_tbl = vmcs_readl(GUEST_INTR_SSP_TABLE);
> +	}
Yang Weijiang April 21, 2021, 9:08 a.m. UTC | #2
On Tue, Apr 20, 2021 at 05:35:01PM +0000, Sean Christopherson wrote:
> On Fri, Apr 09, 2021, Yang Weijiang wrote:
> > These fields are rarely updated by L1 QEMU/KVM, sync them when L1 is trying to
> > read/write them and after they're changed. If CET guest entry-load bit is not
> > set by L1 guest, migrate them to L2 manaully.
> > 
> > Opportunistically remove one blank line in previous patch.
> > 
> > Suggested-by: Sean Christopherson <seanjc@google.com>
> > Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
> > ---
> >  arch/x86/kvm/cpuid.c      |  1 -
> >  arch/x86/kvm/vmx/nested.c | 30 ++++++++++++++++++++++++++++++
> >  arch/x86/kvm/vmx/vmx.h    |  3 +++
> >  3 files changed, 33 insertions(+), 1 deletion(-)
> > 
> >  	vmx_set_rflags(vcpu, vmcs12->guest_rflags);
> >  
> >  	/* EXCEPTION_BITMAP and CR0_GUEST_HOST_MASK should basically be the
> > @@ -3375,6 +3391,11 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
> >  	if (kvm_mpx_supported() &&
> >  		!(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_BNDCFGS))
> >  		vmx->nested.vmcs01_guest_bndcfgs = vmcs_read64(GUEST_BNDCFGS);
> > +	if (kvm_cet_supported() && !vmx->nested.nested_run_pending) {
> 
> This needs to be:
> 
> 	if (kvm_cet_supported() && (!vmx->nested.nested_run_pending ||
> 	    !(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_CET_STATE)))
> 
> otherwise the vmcs01_* members will be stale when emulating VM-Enter with
> vcmc12.vm_entry_controls.LOAD_CET_STATE=0.
> 
Thanks Sean! Change is included in v6 patch series.

> > +		vmx->nested.vmcs01_guest_ssp = vmcs_readl(GUEST_SSP);
> > +		vmx->nested.vmcs01_guest_s_cet = vmcs_readl(GUEST_S_CET);
> > +		vmx->nested.vmcs01_guest_ssp_tbl = vmcs_readl(GUEST_INTR_SSP_TABLE);
> > +	}
diff mbox series

Patch

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index d191de769093..8692f53b8cd0 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -143,7 +143,6 @@  void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
 		}
 		vcpu->arch.guest_supported_xss =
 			(((u64)best->edx << 32) | best->ecx) & supported_xss;
-
 	} else {
 		vcpu->arch.guest_supported_xss = 0;
 	}
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 9728efd529a1..87beb1c034e1 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2516,6 +2516,13 @@  static void prepare_vmcs02_rare(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
 	vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, vmx->msr_autoload.guest.nr);
 
 	set_cr4_guest_host_mask(vmx);
+
+	if (kvm_cet_supported() && vmx->nested.nested_run_pending &&
+	    (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_CET_STATE)) {
+		vmcs_writel(GUEST_SSP, vmcs12->guest_ssp);
+		vmcs_writel(GUEST_S_CET, vmcs12->guest_s_cet);
+		vmcs_writel(GUEST_INTR_SSP_TABLE, vmcs12->guest_ssp_tbl);
+	}
 }
 
 /*
@@ -2556,6 +2563,15 @@  static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
 	if (kvm_mpx_supported() && (!vmx->nested.nested_run_pending ||
 	    !(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_BNDCFGS)))
 		vmcs_write64(GUEST_BNDCFGS, vmx->nested.vmcs01_guest_bndcfgs);
+
+	if (kvm_cet_supported() && (!vmx->nested.nested_run_pending ||
+	    !(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_CET_STATE))) {
+		vmcs_writel(GUEST_SSP, vmx->nested.vmcs01_guest_ssp);
+		vmcs_writel(GUEST_S_CET, vmx->nested.vmcs01_guest_s_cet);
+		vmcs_writel(GUEST_INTR_SSP_TABLE,
+			    vmx->nested.vmcs01_guest_ssp_tbl);
+	}
+
 	vmx_set_rflags(vcpu, vmcs12->guest_rflags);
 
 	/* EXCEPTION_BITMAP and CR0_GUEST_HOST_MASK should basically be the
@@ -3375,6 +3391,11 @@  enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
 	if (kvm_mpx_supported() &&
 		!(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_BNDCFGS))
 		vmx->nested.vmcs01_guest_bndcfgs = vmcs_read64(GUEST_BNDCFGS);
+	if (kvm_cet_supported() && !vmx->nested.nested_run_pending) {
+		vmx->nested.vmcs01_guest_ssp = vmcs_readl(GUEST_SSP);
+		vmx->nested.vmcs01_guest_s_cet = vmcs_readl(GUEST_S_CET);
+		vmx->nested.vmcs01_guest_ssp_tbl = vmcs_readl(GUEST_INTR_SSP_TABLE);
+	}
 
 	/*
 	 * Overwrite vmcs01.GUEST_CR3 with L1's CR3 if EPT is disabled *and*
@@ -4001,6 +4022,9 @@  static bool is_vmcs12_ext_field(unsigned long field)
 	case GUEST_IDTR_BASE:
 	case GUEST_PENDING_DBG_EXCEPTIONS:
 	case GUEST_BNDCFGS:
+	case GUEST_SSP:
+	case GUEST_INTR_SSP_TABLE:
+	case GUEST_S_CET:
 		return true;
 	default:
 		break;
@@ -4052,6 +4076,12 @@  static void sync_vmcs02_to_vmcs12_rare(struct kvm_vcpu *vcpu,
 		vmcs_readl(GUEST_PENDING_DBG_EXCEPTIONS);
 	if (kvm_mpx_supported())
 		vmcs12->guest_bndcfgs = vmcs_read64(GUEST_BNDCFGS);
+	if (kvm_cet_supported() && (guest_cpuid_has(vcpu, X86_FEATURE_SHSTK) ||
+	    guest_cpuid_has(vcpu, X86_FEATURE_IBT))) {
+		vmcs12->guest_ssp = vmcs_readl(GUEST_SSP);
+		vmcs12->guest_s_cet = vmcs_readl(GUEST_S_CET);
+		vmcs12->guest_ssp_tbl = vmcs_readl(GUEST_INTR_SSP_TABLE);
+	}
 
 	vmx->nested.need_sync_vmcs02_to_vmcs12_rare = false;
 }
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 9d3a557949ac..36dc4fdb0909 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -155,6 +155,9 @@  struct nested_vmx {
 	/* to migrate it to L2 if VM_ENTRY_LOAD_DEBUG_CONTROLS is off */
 	u64 vmcs01_debugctl;
 	u64 vmcs01_guest_bndcfgs;
+	u64 vmcs01_guest_ssp;
+	u64 vmcs01_guest_s_cet;
+	u64 vmcs01_guest_ssp_tbl;
 
 	/* to migrate it to L1 if L2 writes to L1's CR8 directly */
 	int l1_tpr_threshold;