Re: [PATCH qom-cpu 05/11] target-i386: check/enforce: Fix CPUID leaf numbers on error messages

Gleb Natapov
2013-01-06T14:12:54Z

On Fri, Jan 04, 2013 at 08:01:06PM -0200, Eduardo Habkost wrote:
> The -cpu check/enforce warnings are printing incorrect information about the
> missing flags. There are no feature flags on CPUID leaves 0 and 0x80000000, but
> there were references to 0 and 0x80000000 in the table at
> kvm_check_features_against_host().
>
> This changes the model_features_t struct to contain the register number as
> well, so the error messages print the correct CPUID leaf+register information,
> instead of wrong CPUID leaf numbers.
>
> This also changes the format of the error messages, so they follow the
> "CPUID.<leaf>.<register>.<name> [bit <offset>]" convention used on Intel
> documentation. Example output:
>
> $ qemu-system-x86_64 -machine pc-1.0,accel=kvm -cpu Opteron_G4,+ia64,enforce
> warning: host doesn't support requested feature: CPUID.01H:EDX.ia64 [bit 30]
> warning: host doesn't support requested feature: CPUID.01H:ECX.xsave [bit 26]
> warning: host doesn't support requested feature: CPUID.01H:ECX.avx [bit 28]
> warning: host doesn't support requested feature: CPUID.80000001H:ECX.abm [bit 5]
> warning: host doesn't support requested feature: CPUID.80000001H:ECX.sse4a [bit 6]
> warning: host doesn't support requested feature: CPUID.80000001H:ECX.misalignsse [bit 7]
> warning: host doesn't support requested feature: CPUID.80000001H:ECX.3dnowprefetch [bit 8]
> warning: host doesn't support requested feature: CPUID.80000001H:ECX.xop [bit 11]
> warning: host doesn't support requested feature: CPUID.80000001H:ECX.fma4 [bit 16]
> Unable to find x86 CPU definition
> $
>
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Gleb Natapov <gleb@redhat.com>
But see the question below.

> ---
> Cc: Gleb Natapov <gleb@redhat.com>
> Cc: Marcelo Tosatti <mtosatti@redhat.com>
> Cc: kvm@vger.kernel.org
>
> Changes v2:
> - Coding style fixes
> - Add assert() for invalid register numbers on
> unavailable_host_feature()
> ---
> target-i386/cpu.c | 42 +++++++++++++++++++++++++++++++++---------
> target-i386/cpu.h | 3 +++
> 2 files changed, 36 insertions(+), 9 deletions(-)
>
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index e916ae0..c3e5db8 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -124,6 +124,25 @@ static const char *cpuid_7_0_ebx_feature_name[] = {
> NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
> };
>
> +const char *get_register_name_32(unsigned int reg)
> +{
> + static const char *reg_names[CPU_NB_REGS32] = {
> + [R_EAX] = "EAX",
> + [R_ECX] = "ECX",
> + [R_EDX] = "EDX",
> + [R_EBX] = "EBX",
> + [R_ESP] = "ESP",
> + [R_EBP] = "EBP",
> + [R_ESI] = "ESI",
> + [R_EDI] = "EDI",
> + };
> +
> + if (reg > CPU_NB_REGS32) {
> + return NULL;
> + }
> + return reg_names[reg];
> +}
> +
> /* collects per-function cpuid data
> */
> typedef struct model_features_t {
> @@ -132,7 +151,8 @@ typedef struct model_features_t {
> uint32_t check_feat;
> const char **flag_names;
> uint32_t cpuid;
> - } model_features_t;
> + int reg;
> +} model_features_t;
>
> int check_cpuid = 0;
> int enforce_cpuid = 0;
> @@ -923,10 +943,13 @@ static int unavailable_host_feature(struct model_features_t *f, uint32_t mask)
>
> for (i = 0; i < 32; ++i)
> if (1 << i & mask) {
> - fprintf(stderr, "warning: host cpuid %04x_%04x lacks requested"
> - " flag '%s' [0x%08x]\n",
> - f->cpuid >> 16, f->cpuid & 0xffff,
> - f->flag_names[i] ? f->flag_names[i] : "[reserved]", mask);
> + const char *reg = get_register_name_32(f->reg);
> + assert(reg);
> + fprintf(stderr, "warning: host doesn't support requested feature: "
> + "CPUID.%02XH:%s%s%s [bit %d]\n",
> + f->cpuid, reg,
> + f->flag_names[i] ? "." : "",
> + f->flag_names[i] ? f->flag_names[i] : "", i);
> break;
> }
> return 0;
> @@ -945,13 +968,14 @@ static int kvm_check_features_against_host(x86_def_t *guest_def)
> int rv, i;
> struct model_features_t ft[] = {
> {&guest_def->features, &host_def.features,
> - ~0, feature_name, 0x00000000},
> + ~0, feature_name, 0x00000001, R_EDX},
> {&guest_def->ext_features, &host_def.ext_features,
> - ~CPUID_EXT_HYPERVISOR, ext_feature_name, 0x00000001},
> + ~CPUID_EXT_HYPERVISOR, ext_feature_name, 0x00000001, R_ECX},
> {&guest_def->ext2_features, &host_def.ext2_features,
> - ~PPRO_FEATURES, ext2_feature_name, 0x80000000},
> + ~PPRO_FEATURES, ext2_feature_name, 0x80000001, R_EDX},
> {&guest_def->ext3_features, &host_def.ext3_features,
> - ~CPUID_EXT3_SVM, ext3_feature_name, 0x80000001}};
> + ~CPUID_EXT3_SVM, ext3_feature_name, 0x80000001, R_ECX}
Why do we exclude PPRO_FEATURES/CPUID_EXT3_SVM from been checked?

> + };
>
> assert(kvm_enabled());
>
> diff --git a/target-i386/cpu.h b/target-i386/cpu.h
> index 27c8d0c..ab81a5c 100644
> --- a/target-i386/cpu.h
> +++ b/target-i386/cpu.h
> @@ -1221,4 +1221,7 @@ void cpu_report_tpr_access(CPUX86State *env, TPRAccess access);
> void enable_kvm_pv_eoi(void);
> void disable_kvm_mmu_op(void);
>
> +/* Return name of 32-bit register, from a R_* constant */
> +const char *get_register_name_32(unsigned int reg);
> +
> #endif /* CPU_I386_H */
> --
> 1.7.11.7

--
Gleb.