Re: [PATCH RFC 4/5] x86: KVM: add xsetbv to the emulator

Paolo Bonzini
2019-06-20T12:18:50Z

On 20/06/19 13:02, Vitaly Kuznetsov wrote:
> To avoid hardcoding xsetbv length to '3' we need to support decoding it in
> the emulator.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>

Can you also emulate it properly? The code from QEMU's
target/i386/fpu_helper.c can help. :)

Paolo

> ---
> arch/x86/include/asm/kvm_emulate.h | 1 +
> arch/x86/kvm/emulate.c | 9 ++++++++-
> arch/x86/kvm/svm.c | 1 +
> 3 files changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
> index feab24cac610..478f76b0122d 100644
> --- a/arch/x86/include/asm/kvm_emulate.h
> +++ b/arch/x86/include/asm/kvm_emulate.h
> @@ -429,6 +429,7 @@ enum x86_intercept {
> x86_intercept_ins,
> x86_intercept_out,
> x86_intercept_outs,
> + x86_intercept_xsetbv,
>
> nr_x86_intercepts
> };
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index d0d5dd44b4f4..ff25d94df684 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -4393,6 +4393,12 @@ static const struct opcode group7_rm1[] = {
> N, N, N, N, N, N,
> };
>
> +static const struct opcode group7_rm2[] = {
> + N,
> + DI(SrcNone | Priv, xsetbv),
> + N, N, N, N, N, N,
> +};
> +
> static const struct opcode group7_rm3[] = {
> DIP(SrcNone | Prot | Priv, vmrun, check_svme_pa),
> II(SrcNone | Prot | EmulateOnUD, em_hypercall, vmmcall),
> @@ -4482,7 +4488,8 @@ static const struct group_dual group7 = { {
> }, {
> EXT(0, group7_rm0),
> EXT(0, group7_rm1),
> - N, EXT(0, group7_rm3),
> + EXT(0, group7_rm2),
> + EXT(0, group7_rm3),
> II(SrcNone | DstMem | Mov, em_smsw, smsw), N,
> II(SrcMem16 | Mov | Priv, em_lmsw, lmsw),
> EXT(0, group7_rm7),
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index f980fc43372d..39e61029f401 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -6041,6 +6041,7 @@ static const struct __x86_intercept {
> [x86_intercept_ins] = POST_EX(SVM_EXIT_IOIO),
> [x86_intercept_out] = POST_EX(SVM_EXIT_IOIO),
> [x86_intercept_outs] = POST_EX(SVM_EXIT_IOIO),
> + [x86_intercept_xsetbv] = PRE_EX(SVM_EXIT_XSETBV),
> };
>
> #undef PRE_EX
>