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Re: [Qemu-devel] [PATCH v3 uq/master 2/2] x86: cpuid: reconstruct leaf 0
From: |
Gleb Natapov |
Subject: |
Re: [Qemu-devel] [PATCH v3 uq/master 2/2] x86: cpuid: reconstruct leaf 0Dh data |
Date: |
Thu, 3 Oct 2013 13:01:54 +0300 |
On Thu, Oct 03, 2013 at 11:59:24AM +0200, Igor Mammedov wrote:
> On Wed, 2 Oct 2013 17:54:57 +0200
> Paolo Bonzini <address@hidden> wrote:
>
> > The data in leaf 0Dh depends on information from other feature bits.
> > Instead of passing it blindly from the host, compute it based on
> > whether these feature bits are enabled.
> >
> > Signed-off-by: Paolo Bonzini <address@hidden>
> > ---
> > target-i386/cpu.c | 65
> > ++++++++++++++++++++++++++++++++++++++++---------------
> > 1 file changed, 48 insertions(+), 17 deletions(-)
> >
> > diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> > index ac83106..1addb18 100644
> > --- a/target-i386/cpu.c
> > +++ b/target-i386/cpu.c
> > @@ -328,6 +328,15 @@ X86RegisterInfo32 x86_reg_info_32[CPU_NB_REGS32] = {
> > };
> > #undef REGISTER
> >
> > +typedef struct ExtSaveArea {
> > + uint32_t feature, bits;
> > + uint32_t offset, size;
> > +} ExtSaveArea;
> > +
> > +static const ExtSaveArea ext_save_areas[] = {
> > + [2] = { .feature = FEAT_1_ECX, .bits = CPUID_EXT_AVX,
> > + .offset = 0x100, .size = 0x240 },
> > +};
> >
> > const char *get_register_name_32(unsigned int reg)
> > {
> > @@ -2169,29 +2178,51 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t
> > index, uint32_t count,
> > *edx = 0;
> > }
> > break;
> > - case 0xD:
> > + case 0xD: {
> > + KVMState *s = cs->kvm_state;
> > + uint64_t kvm_mask;
> > + int i;
> > +
> > /* Processor Extended State */
> > - if (!(env->features[FEAT_1_ECX] & CPUID_EXT_XSAVE)) {
> > - *eax = 0;
> > - *ebx = 0;
> > - *ecx = 0;
> > - *edx = 0;
> > + *eax = 0;
> > + *ebx = 0;
> > + *ecx = 0;
> > + *edx = 0;
> > + if (!(env->features[FEAT_1_ECX] & CPUID_EXT_XSAVE) ||
> > !kvm_enabled()) {
> > break;
> > }
> > - 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);
> calling kvm_arch_get_supported_cpuid() without kvm_enabled() guard
> could regress TCG mode on non KVM host:
>
But there is kvm_enabled() guard above.
> kvm_arch_get_supported_cpuid -> get_supported_cpuid -> try_get_cpuid ->
> r = kvm_ioctl(s, KVM_GET_SUPPORTED_CPUID, cpuid);
> ...
> if (r < 0) {
> if (r == -E2BIG) {
> g_free(cpuid);
> return NULL;
> } else {
> fprintf(stderr, "KVM_GET_SUPPORTED_CPUID failed: %s\n",
> strerror(-r));
> exit(1);
> ^^^^^^^^^ guest suddenly dies
>
> >
> > - *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 & (XSTATE_FP | XSTATE_SSE);
> > + *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;
> > + }
> > }
> > break;
> > + }
> > case 0x80000000:
> > *eax = env->cpuid_xlevel;
> > *ebx = env->cpuid_vendor1;
--
Gleb.