When LASS is enabled, KVM need apply LASS violation check to instruction
emulations. Add helper for the usage of x86 emulator to perform LASS
protection.
Signed-off-by: Zeng Guang <[email protected]>
Tested-by: Xuelian Guo <[email protected]>
---
arch/x86/kvm/kvm_emulate.h | 1 +
arch/x86/kvm/x86.c | 12 ++++++++++++
2 files changed, 13 insertions(+)
diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h
index f1439ab7c14b..fd1c2b22867e 100644
--- a/arch/x86/kvm/kvm_emulate.h
+++ b/arch/x86/kvm/kvm_emulate.h
@@ -230,6 +230,7 @@ struct x86_emulate_ops {
int (*leave_smm)(struct x86_emulate_ctxt *ctxt);
void (*triple_fault)(struct x86_emulate_ctxt *ctxt);
int (*set_xcr)(struct x86_emulate_ctxt *ctxt, u32 index, u64 xcr);
+ bool (*check_lass)(struct x86_emulate_ctxt *ctxt, u64 access, u64 la, u32 flags);
};
/* Type, address-of, and value of an instruction's operand. */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c0778ca39650..faf01fecc4ca 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8287,6 +8287,17 @@ static void emulator_vm_bugged(struct x86_emulate_ctxt *ctxt)
kvm_vm_bugged(kvm);
}
+static bool emulator_check_lass(struct x86_emulate_ctxt *ctxt,
+ u64 access, u64 la, u32 flags)
+{
+ struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
+
+ if (!is_long_mode(vcpu))
+ return false;
+
+ return static_call(kvm_x86_check_lass)(vcpu, access, la, flags);
+}
+
static const struct x86_emulate_ops emulate_ops = {
.vm_bugged = emulator_vm_bugged,
.read_gpr = emulator_read_gpr,
@@ -8332,6 +8343,7 @@ static const struct x86_emulate_ops emulate_ops = {
.leave_smm = emulator_leave_smm,
.triple_fault = emulator_triple_fault,
.set_xcr = emulator_set_xcr,
+ .check_lass = emulator_check_lass,
};
static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask)
--
2.27.0
On Thu, Jun 01, 2023, Zeng Guang wrote:
> When LASS is enabled, KVM need apply LASS violation check to instruction
> emulations. Add helper for the usage of x86 emulator to perform LASS
> protection.
>
> Signed-off-by: Zeng Guang <[email protected]>
> Tested-by: Xuelian Guo <[email protected]>
> ---
> arch/x86/kvm/kvm_emulate.h | 1 +
> arch/x86/kvm/x86.c | 12 ++++++++++++
> 2 files changed, 13 insertions(+)
>
> diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h
> index f1439ab7c14b..fd1c2b22867e 100644
> --- a/arch/x86/kvm/kvm_emulate.h
> +++ b/arch/x86/kvm/kvm_emulate.h
> @@ -230,6 +230,7 @@ struct x86_emulate_ops {
> int (*leave_smm)(struct x86_emulate_ctxt *ctxt);
> void (*triple_fault)(struct x86_emulate_ctxt *ctxt);
> int (*set_xcr)(struct x86_emulate_ctxt *ctxt, u32 index, u64 xcr);
> + bool (*check_lass)(struct x86_emulate_ctxt *ctxt, u64 access, u64 la, u32 flags);
> };
>
> /* Type, address-of, and value of an instruction's operand. */
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index c0778ca39650..faf01fecc4ca 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8287,6 +8287,17 @@ static void emulator_vm_bugged(struct x86_emulate_ctxt *ctxt)
> kvm_vm_bugged(kvm);
> }
>
> +static bool emulator_check_lass(struct x86_emulate_ctxt *ctxt,
> + u64 access, u64 la, u32 flags)
> +{
> + struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
> +
> + if (!is_long_mode(vcpu))
> + return false;
Likely a moot point if we wrap ->gva_to_gpa(), but most this into the vendor
implementation.
And if we keep these emulator hooks, massage the patch ordering:
1. Add plumbing to emulator to pass new flags
2. Add kvm_x86_ops definition and invocation from emulator
3. Implement and wire up vmx_is_lass_violation()
That way the changes to each area of KVM are better isolated.
> + return static_call(kvm_x86_check_lass)(vcpu, access, la, flags);
> +}
> +
> static const struct x86_emulate_ops emulate_ops = {
> .vm_bugged = emulator_vm_bugged,
> .read_gpr = emulator_read_gpr,
> @@ -8332,6 +8343,7 @@ static const struct x86_emulate_ops emulate_ops = {
> .leave_smm = emulator_leave_smm,
> .triple_fault = emulator_triple_fault,
> .set_xcr = emulator_set_xcr,
> + .check_lass = emulator_check_lass,
> };
>
> static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask)
> --
> 2.27.0
>
On 6/28/2023 2:28 AM, Sean Christopherson wrote:
> On Thu, Jun 01, 2023, Zeng Guang wrote:
>> When LASS is enabled, KVM need apply LASS violation check to instruction
>> emulations. Add helper for the usage of x86 emulator to perform LASS
>> protection.
>>
>> Signed-off-by: Zeng Guang <[email protected]>
>> Tested-by: Xuelian Guo <[email protected]>
>> ---
>> arch/x86/kvm/kvm_emulate.h | 1 +
>> arch/x86/kvm/x86.c | 12 ++++++++++++
>> 2 files changed, 13 insertions(+)
>>
>> diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h
>> index f1439ab7c14b..fd1c2b22867e 100644
>> --- a/arch/x86/kvm/kvm_emulate.h
>> +++ b/arch/x86/kvm/kvm_emulate.h
>> @@ -230,6 +230,7 @@ struct x86_emulate_ops {
>> int (*leave_smm)(struct x86_emulate_ctxt *ctxt);
>> void (*triple_fault)(struct x86_emulate_ctxt *ctxt);
>> int (*set_xcr)(struct x86_emulate_ctxt *ctxt, u32 index, u64 xcr);
>> + bool (*check_lass)(struct x86_emulate_ctxt *ctxt, u64 access, u64 la, u32 flags);
>> };
>>
>> /* Type, address-of, and value of an instruction's operand. */
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index c0778ca39650..faf01fecc4ca 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -8287,6 +8287,17 @@ static void emulator_vm_bugged(struct x86_emulate_ctxt *ctxt)
>> kvm_vm_bugged(kvm);
>> }
>>
>> +static bool emulator_check_lass(struct x86_emulate_ctxt *ctxt,
>> + u64 access, u64 la, u32 flags)
>> +{
>> + struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
>> +
>> + if (!is_long_mode(vcpu))
>> + return false;
> Likely a moot point if we wrap ->gva_to_gpa(), but most this into the vendor
> implementation.
It's right way to move cpu mode check into is_lass_violation().
Previously I was struggling
to expect getting benefit from separate invocation. But it doesn't help
much indeed.
>
> And if we keep these emulator hooks, massage the patch ordering:
>
> 1. Add plumbing to emulator to pass new flags
> 2. Add kvm_x86_ops definition and invocation from emulator
> 3. Implement and wire up vmx_is_lass_violation()
>
> That way the changes to each area of KVM are better isolated.
OK. Will reorganize the patch accordingly.
Thanks.
>> + return static_call(kvm_x86_check_lass)(vcpu, access, la, flags);
>> +}
>> +
>> static const struct x86_emulate_ops emulate_ops = {
>> .vm_bugged = emulator_vm_bugged,
>> .read_gpr = emulator_read_gpr,
>> @@ -8332,6 +8343,7 @@ static const struct x86_emulate_ops emulate_ops = {
>> .leave_smm = emulator_leave_smm,
>> .triple_fault = emulator_triple_fault,
>> .set_xcr = emulator_set_xcr,
>> + .check_lass = emulator_check_lass,
>> };
>>
>> static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask)
>> --
>> 2.27.0
>>