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 <guang.zeng@xxxxxxxxx>
> Tested-by: Xuelian Guo <xuelian.guo@xxxxxxxxx>
> ---
> 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
>
