diff mbox series

[RFC,20/35] KVM: SVM: Add SEV/SEV-ES support for intercepting INVD

Message ID cc70b4ac7119dda48a76b0d3ab6ba99ace3c4b5b.1600114548.git.thomas.lendacky@amd.com (mailing list archive)
State New, archived
Headers show
Series SEV-ES hypervisor support | expand

Commit Message

Tom Lendacky Sept. 14, 2020, 8:15 p.m. UTC 
From: Tom Lendacky <thomas.lendacky@amd.com>

The INVD instruction intercept performs emulation. Emulation can't be done
on an SEV or SEV-ES guest because the guest memory is encrypted.

Provide a specific intercept routine for the INVD intercept. Within this
intercept routine, skip the instruction for an SEV or SEV-ES guest since
it is emulated as a NOP anyway.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 arch/x86/kvm/svm/svm.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

Comments

Sean Christopherson Sept. 14, 2020, 10 p.m. UTC | #1 
On Mon, Sep 14, 2020 at 03:15:34PM -0500, Tom Lendacky wrote:
> From: Tom Lendacky <thomas.lendacky@amd.com>
> 
> The INVD instruction intercept performs emulation. Emulation can't be done
> on an SEV or SEV-ES guest because the guest memory is encrypted.
> 
> Provide a specific intercept routine for the INVD intercept. Within this
> intercept routine, skip the instruction for an SEV or SEV-ES guest since
> it is emulated as a NOP anyway.
> 
> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
> ---
>  arch/x86/kvm/svm/svm.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 37c98e85aa62..ac64a5b128b2 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -2275,6 +2275,17 @@ static int iret_interception(struct vcpu_svm *svm)
>  	return 1;
>  }
>  
> +static int invd_interception(struct vcpu_svm *svm)
> +{
> +	/*
> +	 * Can't do emulation on any type of SEV guest and INVD is emulated
> +	 * as a NOP, so just skip it.
> +	 */
> +	return (sev_guest(svm->vcpu.kvm))

Should this be a standalone/backported fix for SEV?

> +		? kvm_skip_emulated_instruction(&svm->vcpu)
> +		: kvm_emulate_instruction(&svm->vcpu, 0);
> +}
> +
>  static int invlpg_interception(struct vcpu_svm *svm)
>  {
>  	if (!static_cpu_has(X86_FEATURE_DECODEASSISTS))
> @@ -2912,7 +2923,7 @@ static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = {
>  	[SVM_EXIT_RDPMC]			= rdpmc_interception,
>  	[SVM_EXIT_CPUID]			= cpuid_interception,
>  	[SVM_EXIT_IRET]                         = iret_interception,
> -	[SVM_EXIT_INVD]                         = emulate_on_interception,
> +	[SVM_EXIT_INVD]                         = invd_interception,
>  	[SVM_EXIT_PAUSE]			= pause_interception,
>  	[SVM_EXIT_HLT]				= halt_interception,
>  	[SVM_EXIT_INVLPG]			= invlpg_interception,
> -- 
> 2.28.0
>
Tom Lendacky Sept. 15, 2020, 3:08 p.m. UTC | #2 
On 9/14/20 5:00 PM, Sean Christopherson wrote:
> On Mon, Sep 14, 2020 at 03:15:34PM -0500, Tom Lendacky wrote:
>> From: Tom Lendacky <thomas.lendacky@amd.com>
>>
>> The INVD instruction intercept performs emulation. Emulation can't be done
>> on an SEV or SEV-ES guest because the guest memory is encrypted.
>>
>> Provide a specific intercept routine for the INVD intercept. Within this
>> intercept routine, skip the instruction for an SEV or SEV-ES guest since
>> it is emulated as a NOP anyway.
>>
>> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
>> ---
>>  arch/x86/kvm/svm/svm.c | 13 ++++++++++++-
>>  1 file changed, 12 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
>> index 37c98e85aa62..ac64a5b128b2 100644
>> --- a/arch/x86/kvm/svm/svm.c
>> +++ b/arch/x86/kvm/svm/svm.c
>> @@ -2275,6 +2275,17 @@ static int iret_interception(struct vcpu_svm *svm)
>>  	return 1;
>>  }
>>  
>> +static int invd_interception(struct vcpu_svm *svm)
>> +{
>> +	/*
>> +	 * Can't do emulation on any type of SEV guest and INVD is emulated
>> +	 * as a NOP, so just skip it.
>> +	 */
>> +	return (sev_guest(svm->vcpu.kvm))
> 
> Should this be a standalone/backported fix for SEV?

Yes. Let me split it out and send it separately.

Thanks,
Tom

> 
>> +		? kvm_skip_emulated_instruction(&svm->vcpu)
>> +		: kvm_emulate_instruction(&svm->vcpu, 0);
>> +}
>> +
>>  static int invlpg_interception(struct vcpu_svm *svm)
>>  {
>>  	if (!static_cpu_has(X86_FEATURE_DECODEASSISTS))
>> @@ -2912,7 +2923,7 @@ static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = {
>>  	[SVM_EXIT_RDPMC]			= rdpmc_interception,
>>  	[SVM_EXIT_CPUID]			= cpuid_interception,
>>  	[SVM_EXIT_IRET]                         = iret_interception,
>> -	[SVM_EXIT_INVD]                         = emulate_on_interception,
>> +	[SVM_EXIT_INVD]                         = invd_interception,
>>  	[SVM_EXIT_PAUSE]			= pause_interception,
>>  	[SVM_EXIT_HLT]				= halt_interception,
>>  	[SVM_EXIT_INVLPG]			= invlpg_interception,
>> -- 
>> 2.28.0
>>
diff mbox series

Patch

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 37c98e85aa62..ac64a5b128b2 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2275,6 +2275,17 @@  static int iret_interception(struct vcpu_svm *svm)
 	return 1;
 }
 
+static int invd_interception(struct vcpu_svm *svm)
+{
+	/*
+	 * Can't do emulation on any type of SEV guest and INVD is emulated
+	 * as a NOP, so just skip it.
+	 */
+	return (sev_guest(svm->vcpu.kvm))
+		? kvm_skip_emulated_instruction(&svm->vcpu)
+		: kvm_emulate_instruction(&svm->vcpu, 0);
+}
+
 static int invlpg_interception(struct vcpu_svm *svm)
 {
 	if (!static_cpu_has(X86_FEATURE_DECODEASSISTS))
@@ -2912,7 +2923,7 @@  static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = {
 	[SVM_EXIT_RDPMC]			= rdpmc_interception,
 	[SVM_EXIT_CPUID]			= cpuid_interception,
 	[SVM_EXIT_IRET]                         = iret_interception,
-	[SVM_EXIT_INVD]                         = emulate_on_interception,
+	[SVM_EXIT_INVD]                         = invd_interception,
 	[SVM_EXIT_PAUSE]			= pause_interception,
 	[SVM_EXIT_HLT]				= halt_interception,
 	[SVM_EXIT_INVLPG]			= invlpg_interception,