On Wed, Oct 02, 2013 at 05:37:31PM +0200, Paolo Bonzini wrote:
> Il 02/10/2013 17:21, Gleb Natapov ha scritto:
> >> - if (kvm_enabled()) {
> >> - KVMState *s = cs->kvm_state;
> >> + kvm_mask =
> >> + kvm_arch_get_supported_cpuid(s, 0xd, 0, R_EAX) |
> >> + ((uint64_t)kvm_arch_get_supported_cpuid(s, 0xd, 0, R_EDX) << 32);
> >>
> >> - *eax = kvm_arch_get_supported_cpuid(s, 0xd, count, R_EAX);
> >> - *ebx = kvm_arch_get_supported_cpuid(s, 0xd, count, R_EBX);
> >> - *ecx = kvm_arch_get_supported_cpuid(s, 0xd, count, R_ECX);
> >> - *edx = kvm_arch_get_supported_cpuid(s, 0xd, count, R_EDX);
> >> - } else {
> >> - *eax = 0;
> >> - *ebx = 0;
> >> - *ecx = 0;
> >> - *edx = 0;
> >> + if (count == 0) {
> >> + *ecx = 0x240;
> >> + for (i = 2; i < ARRAY_SIZE(ext_save_areas); i++) {
> >> + const ExtSaveArea *esa = &ext_save_areas[i];
> >> + if ((env->features[esa->feature] & esa->bits) == esa->bits &&
> >> + (kvm_mask & (1 << i)) != 0) {
> >> + if (i < 32) {
> >> + *eax |= 1 << i;
> >> + } else {
> >> + *edx |= 1 << (i - 32);
> >> + }
> >> + *ecx = MAX(*ecx, esa->offset + esa->size);
> >> + }
> >> + }
> >> + *eax |= kvm_mask & 3;
> > Lets use define from previous patch.
>
> Right.
>
> >> + *ebx = *ecx;
> >> + } else if (count == 1) {
> >> + *eax = kvm_arch_get_supported_cpuid(s, 0xd, 1, R_EAX);
> >> + } else if (count < ARRAY_SIZE(ext_save_areas)) {
> >> + const ExtSaveArea *esa = &ext_save_areas[count];
> >> + if ((env->features[esa->feature] & esa->bits) == esa->bits &&
> >> + (kvm_mask & (1 << count)) != 0) {
> >> + *eax = esa->offset;
> >> + *ebx = esa->size;
> > Why do you hard code them instead of querying kernel? What if they
> > depend on cpu type? (well if this happens we can forget about
> > migration, but still...)
>
> HPA confirmed (on xen-devel) that they will not depend on the CPU type.
> All offsets are documented in the SDM and in the additional Skylake
> manual except for MPX, and he reported that he'd ask for MPX to be
> documented as well. As you said, if they changed it would be a total mess.
>
> I hardcoded them because this is not KVM-specific knowledge. TCG could
> in principle reuse the same code, just skipping the part where it masks
> away features not supported by KVM.
>
OK. Can you send new version with defines please?
--
Gleb.
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