[v2] KVM: nVMX: Sync L2 guest CET states between L1/L2
diff mbox series

Message ID 20210225030951.17099-2-weijiang.yang@intel.com
State New, archived
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Series
  • [v2] KVM: nVMX: Sync L2 guest CET states between L1/L2
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Commit Message

Yang Weijiang Feb. 25, 2021, 3:09 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.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>

change in v2:
 - Per Sean's review feedback, change CET guest states as rarely-updated fields.
   And also migrate L1's CET states to L2 if the entry-load bit is not set.
 - Opportunistically removed one blank line.
---
 arch/x86/kvm/cpuid.c      |  1 -
 arch/x86/kvm/vmx/nested.c | 29 +++++++++++++++++++++++++++++
 arch/x86/kvm/vmx/vmx.h    |  3 +++
 3 files changed, 32 insertions(+), 1 deletion(-)

Comments

Sean Christopherson March 1, 2021, 5:46 p.m. UTC | #1
+Vitaly

On Thu, Feb 25, 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.
> 
> Suggested-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
> 
> change in v2:
>  - Per Sean's review feedback, change CET guest states as rarely-updated fields.
>    And also migrate L1's CET states to L2 if the entry-load bit is not set.
>  - Opportunistically removed one blank line.
> ---
>  arch/x86/kvm/cpuid.c      |  1 -
>  arch/x86/kvm/vmx/nested.c | 29 +++++++++++++++++++++++++++++
>  arch/x86/kvm/vmx/vmx.h    |  3 +++
>  3 files changed, 32 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 46087bca9418..afc97122c05c 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..1703b8874fad 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -2516,6 +2516,12 @@ 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()) {

This needs to be conditioned on CET coming from vmcs12, it's on the loading of
host state on VM-Exit that is unconditional (if CET is supported).

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

I also assume these should be guarded by one of the eVMCS fields, though a quick
search of the public docs didn't provide a hit on the CET fields.

Vitaly, any idea if these will be GUEST_GRP2 or something else?

> +		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);
> +	}
>  }
Yang Weijiang March 2, 2021, 9:05 a.m. UTC | #2
On Mon, Mar 01, 2021 at 09:46:19AM -0800, Sean Christopherson wrote:
> +Vitaly
> 
> On Thu, Feb 25, 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.
> > 
> > Suggested-by: Sean Christopherson <seanjc@google.com>
> > Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
> > 
> > change in v2:
> >  - Per Sean's review feedback, change CET guest states as rarely-updated fields.
> >    And also migrate L1's CET states to L2 if the entry-load bit is not set.
> >  - Opportunistically removed one blank line.
> > ---
> >  arch/x86/kvm/cpuid.c      |  1 -
> >  arch/x86/kvm/vmx/nested.c | 29 +++++++++++++++++++++++++++++
> >  arch/x86/kvm/vmx/vmx.h    |  3 +++
> >  3 files changed, 32 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> > index 46087bca9418..afc97122c05c 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..1703b8874fad 100644
> > --- a/arch/x86/kvm/vmx/nested.c
> > +++ b/arch/x86/kvm/vmx/nested.c
> > @@ -2516,6 +2516,12 @@ 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()) {
> 
> This needs to be conditioned on CET coming from vmcs12, it's on the loading of
> host state on VM-Exit that is unconditional (if CET is supported).
> 
> 	if (kvm_cet_supported() && vmx->nested.nested_run_pending &&
> 	    (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_CET_STATE)) {
>
Thanks Sean! Will change it.

> I also assume these should be guarded by one of the eVMCS fields, though a quick
> search of the public docs didn't provide a hit on the CET fields.
>

I got some description from MSFT as below, do you mean that:

GuestSsp uses clean field GUEST_BASIC (bit 10)
GuestSCet/GuestInterruptSspTableAddr uses GUEST_GRP1 (bit 11)
HostSCet/HostSsp/HostInterruptSspTableAddr uses HOST_GRP1 (bit 14)

If it is, should these go into separate patch series for Hyper-v nested
support? I have some pending patches for the enabling.

> Vitaly, any idea if these will be GUEST_GRP2 or something else?
> 
> > +		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);
> > +	}
> >  }
Paolo Bonzini March 2, 2021, 9:33 a.m. UTC | #3
On 02/03/21 10:05, Yang Weijiang wrote:
> I got some description from MSFT as below, do you mean that:
> 
> GuestSsp uses clean field GUEST_BASIC (bit 10)
> GuestSCet/GuestInterruptSspTableAddr uses GUEST_GRP1 (bit 11)
> HostSCet/HostSsp/HostInterruptSspTableAddr uses HOST_GRP1 (bit 14)
> 
> If it is, should these go into separate patch series for Hyper-v nested
> support? I have some pending patches for the enabling.

Yes, it should be a separate patch.  The main patch however should add 
the CET fields to EVMCS1_UNSUPPORTED_VMENTRY_CTRL and 
EVMCS1_UNSUPPORTED_VMEXIT_CTRL.

Thanks,

Paolo
Vitaly Kuznetsov March 2, 2021, 10:35 a.m. UTC | #4
Sean Christopherson <seanjc@google.com> writes:

> +Vitaly
>
> On Thu, Feb 25, 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.
>> 
>> Suggested-by: Sean Christopherson <seanjc@google.com>
>> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
>> 
>> change in v2:
>>  - Per Sean's review feedback, change CET guest states as rarely-updated fields.
>>    And also migrate L1's CET states to L2 if the entry-load bit is not set.
>>  - Opportunistically removed one blank line.
>> ---
>>  arch/x86/kvm/cpuid.c      |  1 -
>>  arch/x86/kvm/vmx/nested.c | 29 +++++++++++++++++++++++++++++
>>  arch/x86/kvm/vmx/vmx.h    |  3 +++
>>  3 files changed, 32 insertions(+), 1 deletion(-)
>> 
>> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
>> index 46087bca9418..afc97122c05c 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..1703b8874fad 100644
>> --- a/arch/x86/kvm/vmx/nested.c
>> +++ b/arch/x86/kvm/vmx/nested.c
>> @@ -2516,6 +2516,12 @@ 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()) {
>
> This needs to be conditioned on CET coming from vmcs12, it's on the loading of
> host state on VM-Exit that is unconditional (if CET is supported).
>
> 	if (kvm_cet_supported() && vmx->nested.nested_run_pending &&
> 	    (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_CET_STATE)) {
>
> I also assume these should be guarded by one of the eVMCS fields, though a quick
> search of the public docs didn't provide a hit on the CET fields.
>
> Vitaly, any idea if these will be GUEST_GRP2 or something else?
>

The latest published TLFS I see is 6.0b and it doesn't list anything CET
related in eVMCS v1.0 :-( So I agree with Paolo: we just need to adjust
EVMCS1_UNSUPPORTED_VMENTRY_CTRL/ EVMCS1_UNSUPPORTED_VMEXIT_CTRL for now
and enable it separately later.

>> +		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);
>> +	}
>>  }
>
Yang Weijiang March 3, 2021, 6:09 a.m. UTC | #5
On Tue, Mar 02, 2021 at 11:35:41AM +0100, Vitaly Kuznetsov wrote:
> Sean Christopherson <seanjc@google.com> writes:
> 
> > +Vitaly
> >
> > On Thu, Feb 25, 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.
> >> 
> >> Suggested-by: Sean Christopherson <seanjc@google.com>
> >> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
> >> 
> >> change in v2:
> >>  - Per Sean's review feedback, change CET guest states as rarely-updated fields.
> >>    And also migrate L1's CET states to L2 if the entry-load bit is not set.
> >>  - Opportunistically removed one blank line.
> >> ---
> >>  arch/x86/kvm/cpuid.c      |  1 -
> >>  arch/x86/kvm/vmx/nested.c | 29 +++++++++++++++++++++++++++++
> >>  arch/x86/kvm/vmx/vmx.h    |  3 +++
> >>  3 files changed, 32 insertions(+), 1 deletion(-)
> >> 
> >> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> >> index 46087bca9418..afc97122c05c 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..1703b8874fad 100644
> >> --- a/arch/x86/kvm/vmx/nested.c
> >> +++ b/arch/x86/kvm/vmx/nested.c
> >> @@ -2516,6 +2516,12 @@ 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()) {
> >
> > This needs to be conditioned on CET coming from vmcs12, it's on the loading of
> > host state on VM-Exit that is unconditional (if CET is supported).
> >
> > 	if (kvm_cet_supported() && vmx->nested.nested_run_pending &&
> > 	    (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_CET_STATE)) {
> >
> > I also assume these should be guarded by one of the eVMCS fields, though a quick
> > search of the public docs didn't provide a hit on the CET fields.
> >
> > Vitaly, any idea if these will be GUEST_GRP2 or something else?
> >
> 
> The latest published TLFS I see is 6.0b and it doesn't list anything CET
> related in eVMCS v1.0 :-( So I agree with Paolo: we just need to adjust
> EVMCS1_UNSUPPORTED_VMENTRY_CTRL/ EVMCS1_UNSUPPORTED_VMEXIT_CTRL for now
> and enable it separately later.
>

Thanks Vitaly and Paolo.
New patches have been sent to community.

> >> +		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);
> >> +	}
> >>  }
> >
> 
> -- 
> Vitaly

Patch
diff mbox series

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 46087bca9418..afc97122c05c 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..1703b8874fad 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2516,6 +2516,12 @@  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()) {
+		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 +2562,15 @@  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 +3390,12 @@  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() &&
+		!(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_CET_STATE)) {
+		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 +4076,11 @@  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()) {
+		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;