On 22/10/20 06:01, Luwei Kang wrote:
> PTWRITE provides a mechanism by which software can instrument the
> Intel PT trace. The current implementation will mask off this
> feature when the PTWRITE is supported on the host because of the
> Intel PT CPUID is a constant value(ICX CPUID) in qemu. This patch
> will expose the PTWRITE feature to the guest.
>
> Signed-off-by: Luwei Kang
> ---
> target/i386/cpu.c | 24
> target/i386/cpu.h | 4
> 2 files changed, 28 insertions(+)
>
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index aeabdd5bd4..242ba8a870 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -672,6 +672,7 @@ static void x86_cpu_vendor_words2str(char *dst, uint32_t
> vendor1,
> #define TCG_XSAVE_FEATURES (CPUID_XSAVE_XSAVEOPT | CPUID_XSAVE_XGETBV1)
>/* missing:
>CPUID_XSAVE_XSAVEC, CPUID_XSAVE_XSAVES */
> +#define TCG_14_0_EBX_FEATURES 0
> #define TCG_14_0_ECX_FEATURES 0
>
> typedef enum FeatureWordType {
> @@ -1302,6 +1303,26 @@ static FeatureWordInfo
> feature_word_info[FEATURE_WORDS] = {
> }
> },
>
> +[FEAT_14_0_EBX] = {
> +.type = CPUID_FEATURE_WORD,
> +.feat_names = {
> +NULL, NULL, NULL, NULL,
> +"ptwrite", NULL, NULL, NULL,
> +NULL, NULL, NULL, NULL,
> +NULL, NULL, NULL, NULL,
> +NULL, NULL, NULL, NULL,
> +NULL, NULL, NULL, NULL,
> +NULL, NULL, NULL, NULL,
> +NULL, NULL, NULL, NULL,
> +},
> +.cpuid = {
> +.eax = 0x14,
> +.needs_ecx = true, .ecx = 0,
> +.reg = R_EBX,
> +},
> +.tcg_features = TCG_14_0_EBX_FEATURES,
> +},
> +
Please add a dependency on the processor tracing flag too.
Paolo
> [FEAT_14_0_ECX] = {
> .type = CPUID_FEATURE_WORD,
> .feat_names = {
> @@ -5764,6 +5785,9 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
> uint32_t count,
> *eax = INTEL_PT_MAX_SUBLEAF;
> *ebx = INTEL_PT_MINIMAL_EBX;
> *ecx = INTEL_PT_MINIMAL_ECX;
> +if (env->features[FEAT_14_0_EBX] & CPUID_14_0_EBX_PTWRITE) {
> +*ebx |= CPUID_14_0_EBX_PTWRITE;
> +}
> if (env->features[FEAT_14_0_ECX] & CPUID_14_0_ECX_LIP) {
> *ecx |= CPUID_14_0_ECX_LIP;
> }
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 1fcd93e39a..9fffe6eb6f 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -541,6 +541,7 @@ typedef enum FeatureWord {
> FEAT_VMX_EPT_VPID_CAPS,
> FEAT_VMX_BASIC,
> FEAT_VMX_VMFUNC,
> +FEAT_14_0_EBX,
> FEAT_14_0_ECX,
> FEATURE_WORDS,
> } FeatureWord;
> @@ -798,6 +799,9 @@ typedef uint64_t FeatureWordArray[FEATURE_WORDS];
> /* AVX512 BFloat16 Instruction */
> #define CPUID_7_1_EAX_AVX512_BF16 (1U << 5)
>
> +/* Intel PT support PTWRITE */
> +#define CPUID_14_0_EBX_PTWRITE (1U << 4)
> +
> /* Packets which contain IP payload have LIP values */
> #define CPUID_14_0_ECX_LIP (1U << 31)
>
>
