> From: Zhong, Yang <yang.zh...@intel.com>
> Sent: Friday, January 7, 2022 5:31 PM
>
> From: Jing Liu <jing2....@intel.com>
>
> The extended state subleaves (EAX=0Dh, ECX=n, n>1).ECX[1]
> are all zero, while spec actually introduces that bit 01
> should indicate if the extended state component locates
> on the next 64-byte boundary following the preceding state
> component when the compacted format of an XSAVE area is
> used.
Above would read clearer if you revise to:
"The extended state subleaves (EAX=0Dh, ECX=n, n>1).ECX[1]
indicate whether the extended state component locates
on the next 64-byte boundary following the preceding state
component when the compacted format of an XSAVE area is
used.
But ECX[1] is always cleared in current implementation."
>
> Fix the subleaves value according to the host supported
> cpuid. The upcoming AMX feature would be the first one
> using it.
>
> Signed-off-by: Jing Liu <jing2....@intel.com>
> Signed-off-by: Yang Zhong <yang.zh...@intel.com>
> ---
> target/i386/cpu.h | 1 +
> target/i386/cpu.c | 1 +
> target/i386/kvm/kvm-cpu.c | 3 +++
> 3 files changed, 5 insertions(+)
>
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 04f2b790c9..7f9700544f 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -1354,6 +1354,7 @@ QEMU_BUILD_BUG_ON(sizeof(XSavePKRU) != 0x8);
> typedef struct ExtSaveArea {
> uint32_t feature, bits;
> uint32_t offset, size;
> + uint32_t need_align;
> } ExtSaveArea;
>
> #define XSAVE_STATE_AREA_COUNT (XSTATE_PKRU_BIT + 1)
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index aa9e636800..47bc4d5c1a 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -5487,6 +5487,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t
> index, uint32_t count,
> const ExtSaveArea *esa = &x86_ext_save_areas[count];
> *eax = esa->size;
> *ebx = esa->offset;
> + *ecx = esa->need_align << 1;
> }
> }
> break;
> diff --git a/target/i386/kvm/kvm-cpu.c b/target/i386/kvm/kvm-cpu.c
> index d95028018e..6c4c1c6f9d 100644
> --- a/target/i386/kvm/kvm-cpu.c
> +++ b/target/i386/kvm/kvm-cpu.c
> @@ -105,6 +105,9 @@ static void kvm_cpu_xsave_init(void)
> assert(esa->size == sz);
> esa->offset = kvm_arch_get_supported_cpuid(s, 0xd, i, R_EBX);
> }
> +
> + uint32_t ecx = kvm_arch_get_supported_cpuid(s, 0xd, i, R_ECX);
> + esa->need_align = ecx & (1u << 1) ? 1 : 0;
> }
> }
> }
