diff mbox series

[v15,14/14] KVM: x86: Save/Restore GUEST_SSP to/from SMRAM

Message ID 20210203113421.5759-15-weijiang.yang@intel.com (mailing list archive)
State New, archived
Headers show
Series Introduce support for guest CET feature | expand

Commit Message

Yang Weijiang Feb. 3, 2021, 11:34 a.m. UTC
Save GUEST_SSP to SMRAM when guest exits to SMM due to SMI and restore it
when guest exits SMM to interrupted normal non-root mode.

Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
---
 arch/x86/kvm/emulate.c | 11 +++++++++++
 arch/x86/kvm/x86.c     | 10 ++++++++++
 2 files changed, 21 insertions(+)

Comments

Paolo Bonzini Feb. 3, 2021, 12:07 p.m. UTC | #1
On 03/02/21 12:34, Yang Weijiang wrote:
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 22eb6b8626a8..f63b713cd71f 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8592,6 +8592,16 @@ static void enter_smm_save_state_64(struct kvm_vcpu *vcpu, char *buf)
>   
>   	for (i = 0; i < 6; i++)
>   		enter_smm_save_seg_64(vcpu, buf, i);
> +
> +	if (kvm_cet_supported()) {
> +		struct msr_data msr;
> +
> +		msr.index = MSR_KVM_GUEST_SSP;
> +		msr.host_initiated = true;
> +		/* GUEST_SSP is stored in VMCS at vm-exit. */
> +		kvm_x86_ops.get_msr(vcpu, &msr);
> +		put_smstate(u64, buf, 0x7ec8, msr.data);
> +	}
>   }
>   #endif
>   
> 

0x7ec8 is used for I/O instruction restart and auto-halt restart. 
0x7f08 is a free spot.  We should really document the KVM state save 
area format.

Paolo
Yang Weijiang Feb. 3, 2021, 12:59 p.m. UTC | #2
On Wed, Feb 03, 2021 at 01:07:53PM +0100, Paolo Bonzini wrote:
> On 03/02/21 12:34, Yang Weijiang wrote:
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index 22eb6b8626a8..f63b713cd71f 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -8592,6 +8592,16 @@ static void enter_smm_save_state_64(struct kvm_vcpu *vcpu, char *buf)
> >   	for (i = 0; i < 6; i++)
> >   		enter_smm_save_seg_64(vcpu, buf, i);
> > +
> > +	if (kvm_cet_supported()) {
> > +		struct msr_data msr;
> > +
> > +		msr.index = MSR_KVM_GUEST_SSP;
> > +		msr.host_initiated = true;
> > +		/* GUEST_SSP is stored in VMCS at vm-exit. */
> > +		kvm_x86_ops.get_msr(vcpu, &msr);
> > +		put_smstate(u64, buf, 0x7ec8, msr.data);
> > +	}
> >   }
> >   #endif
> > 
> 
> 0x7ec8 is used for I/O instruction restart and auto-halt restart. 0x7f08 is
> a free spot.  We should really document the KVM state save area format.
Thanks for catching the documentation error! 
> 
> Paolo
diff mbox series

Patch

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 56cae1ff9e3f..6d4a3181d8bd 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2615,6 +2615,17 @@  static int rsm_load_state_64(struct x86_emulate_ctxt *ctxt,
 			return r;
 	}
 
+	if (kvm_cet_supported()) {
+		struct msr_data msr;
+
+		val = GET_SMSTATE(u64, smstate, 0x7ec8);
+		msr.index = MSR_KVM_GUEST_SSP;
+		msr.host_initiated = true;
+		msr.data = val;
+		/* Mimic host_initiated access to bypass ssp access check. */
+		kvm_x86_ops.set_msr(ctxt->vcpu, &msr);
+	}
+
 	return X86EMUL_CONTINUE;
 }
 #endif
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 22eb6b8626a8..f63b713cd71f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8592,6 +8592,16 @@  static void enter_smm_save_state_64(struct kvm_vcpu *vcpu, char *buf)
 
 	for (i = 0; i < 6; i++)
 		enter_smm_save_seg_64(vcpu, buf, i);
+
+	if (kvm_cet_supported()) {
+		struct msr_data msr;
+
+		msr.index = MSR_KVM_GUEST_SSP;
+		msr.host_initiated = true;
+		/* GUEST_SSP is stored in VMCS at vm-exit. */
+		kvm_x86_ops.get_msr(vcpu, &msr);
+		put_smstate(u64, buf, 0x7ec8, msr.data);
+	}
 }
 #endif