On Thu, Sep 05, 2013 at 03:06:21PM +0200, Paolo Bonzini wrote:
> On KVM, the KVM_SET_XSAVE would be executed with a 0 xstate_bv,
> and not restore anything.
>
XRSTOR restores FP/SSE state to reset state if no bits are set in
xstate_bv. This is what should happen on reset, no?
> Since FP and SSE data are always valid, set them in xstate_bv at reset
> time. In fact, that value is the same that KVM_GET_XSAVE returns on
> pre-XSAVE hosts.
It is needed for migration between non xsave host to xsave host.
>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> ---
> target-i386/cpu.c | 1 +
> target-i386/cpu.h | 5 +++++
> 2 files changed, 6 insertions(+)
>
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index c36345e..ac83106 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -2386,6 +2386,7 @@ static void x86_cpu_reset(CPUState *s)
> env->fpuc = 0x37f;
>
> env->mxcsr = 0x1f80;
> + env->xstate_bv = XSTATE_FP | XSTATE_SSE;
>
> env->pat = 0x0007040600070406ULL;
> env->msr_ia32_misc_enable = MSR_IA32_MISC_ENABLE_DEFAULT;
> diff --git a/target-i386/cpu.h b/target-i386/cpu.h
> index 5723eff..a153078 100644
> --- a/target-i386/cpu.h
> +++ b/target-i386/cpu.h
> @@ -380,6 +380,11 @@
>
> #define MSR_VM_HSAVE_PA 0xc0010117
>
> +#define XSTATE_SUPPORTED (XSTATE_FP|XSTATE_SSE|XSTATE_YMM)
Supported by whom? By QEMU? We should filer unsupported bits from CPUID.0D then too.
> +#define XSTATE_FP 1
> +#define XSTATE_SSE 2
> +#define XSTATE_YMM 4
> +
> /* CPUID feature words */
> typedef enum FeatureWord {
> FEAT_1_EDX, /* CPUID[1].EDX */
> --
> 1.8.3.1
>
--
Gleb.
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