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Re: [Qemu-devel] [PATCH] i386: Introduce ARAT CPU feature
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From: |
Paolo Bonzini |
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Subject: |
Re: [Qemu-devel] [PATCH] i386: Introduce ARAT CPU feature |
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Date: |
Mon, 25 May 2015 15:23:39 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 |
On 24/05/2015 17:16, Jan Kiszka wrote:
> From: Jan Kiszka <address@hidden>
>
> ARAT signals that the APIC timer does not stop in power saving states.
> As our APICs are emulated, it's fine to expose this feature to guests,
> at least when asking for KVM host features or with CPU types that
> include the flag. The exact model number that introduced the feature is
> not known, but reports can be found that it's at least available since
> Sandy Bridge.
>
> Signed-off-by: Jan Kiszka <address@hidden>
This looks good, but you need to disable it in older machine types.
Paolo
> ---
> target-i386/cpu.c | 33 ++++++++++++++++++++++++++++++++-
> target-i386/cpu.h | 3 +++
> target-i386/kvm.c | 2 ++
> 3 files changed, 37 insertions(+), 1 deletion(-)
>
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index 3305e09..e435a08 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -284,6 +284,17 @@ static const char *cpuid_xsave_feature_name[] = {
> NULL, NULL, NULL, NULL,
> };
>
> +static const char *cpuid_6_feature_name[] = {
> + NULL, NULL, "arat", 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, NULL, NULL,
> +};
> +
> #define I486_FEATURES (CPUID_FP87 | CPUID_VME | CPUID_PSE)
> #define PENTIUM_FEATURES (I486_FEATURES | CPUID_DE | CPUID_TSC | \
> CPUID_MSR | CPUID_MCE | CPUID_CX8 | CPUID_MMX | CPUID_APIC)
> @@ -339,6 +350,7 @@ static const char *cpuid_xsave_feature_name[] = {
> CPUID_7_0_EBX_ERMS, CPUID_7_0_EBX_INVPCID, CPUID_7_0_EBX_RTM,
> CPUID_7_0_EBX_RDSEED */
> #define TCG_APM_FEATURES 0
> +#define TCG_6_EAX_FEATURES CPUID_6_EAX_ARAT
>
>
> typedef struct FeatureWordInfo {
> @@ -408,6 +420,11 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS]
> = {
> .cpuid_reg = R_EAX,
> .tcg_features = 0,
> },
> + [FEAT_6_EAX] = {
> + .feat_names = cpuid_6_feature_name,
> + .cpuid_eax = 6, .cpuid_reg = R_EAX,
> + .tcg_features = TCG_6_EAX_FEATURES,
> + },
> };
>
> typedef struct X86RegisterInfo32 {
> @@ -1001,6 +1018,8 @@ static X86CPUDefinition builtin_x86_defs[] = {
> CPUID_EXT2_LM | CPUID_EXT2_SYSCALL | CPUID_EXT2_NX,
> .features[FEAT_8000_0001_ECX] =
> CPUID_EXT3_LAHF_LM,
> + .features[FEAT_6_EAX] =
> + CPUID_6_EAX_ARAT,
> .xlevel = 0x8000000A,
> .model_id = "Westmere E56xx/L56xx/X56xx (Nehalem-C)",
> },
> @@ -1030,6 +1049,8 @@ static X86CPUDefinition builtin_x86_defs[] = {
> CPUID_EXT3_LAHF_LM,
> .features[FEAT_XSAVE] =
> CPUID_XSAVE_XSAVEOPT,
> + .features[FEAT_6_EAX] =
> + CPUID_6_EAX_ARAT,
> .xlevel = 0x8000000A,
> .model_id = "Intel Xeon E312xx (Sandy Bridge)",
> },
> @@ -1062,6 +1083,8 @@ static X86CPUDefinition builtin_x86_defs[] = {
> CPUID_EXT3_LAHF_LM,
> .features[FEAT_XSAVE] =
> CPUID_XSAVE_XSAVEOPT,
> + .features[FEAT_6_EAX] =
> + CPUID_6_EAX_ARAT,
> .xlevel = 0x8000000A,
> .model_id = "Intel Xeon E3-12xx v2 (Ivy Bridge)",
> },
> @@ -1096,6 +1119,8 @@ static X86CPUDefinition builtin_x86_defs[] = {
> CPUID_7_0_EBX_BMI2 | CPUID_7_0_EBX_ERMS | CPUID_7_0_EBX_INVPCID,
> .features[FEAT_XSAVE] =
> CPUID_XSAVE_XSAVEOPT,
> + .features[FEAT_6_EAX] =
> + CPUID_6_EAX_ARAT,
> .xlevel = 0x8000000A,
> .model_id = "Intel Core Processor (Haswell, no TSX)",
> }, {
> @@ -1130,6 +1155,8 @@ static X86CPUDefinition builtin_x86_defs[] = {
> CPUID_7_0_EBX_RTM,
> .features[FEAT_XSAVE] =
> CPUID_XSAVE_XSAVEOPT,
> + .features[FEAT_6_EAX] =
> + CPUID_6_EAX_ARAT,
> .xlevel = 0x8000000A,
> .model_id = "Intel Core Processor (Haswell)",
> },
> @@ -1166,6 +1193,8 @@ static X86CPUDefinition builtin_x86_defs[] = {
> CPUID_7_0_EBX_SMAP,
> .features[FEAT_XSAVE] =
> CPUID_XSAVE_XSAVEOPT,
> + .features[FEAT_6_EAX] =
> + CPUID_6_EAX_ARAT,
> .xlevel = 0x8000000A,
> .model_id = "Intel Core Processor (Broadwell, no TSX)",
> },
> @@ -1202,6 +1231,8 @@ static X86CPUDefinition builtin_x86_defs[] = {
> CPUID_7_0_EBX_SMAP,
> .features[FEAT_XSAVE] =
> CPUID_XSAVE_XSAVEOPT,
> + .features[FEAT_6_EAX] =
> + CPUID_6_EAX_ARAT,
> .xlevel = 0x8000000A,
> .model_id = "Intel Core Processor (Broadwell)",
> },
> @@ -2358,7 +2389,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
> uint32_t count,
> break;
> case 6:
> /* Thermal and Power Leaf */
> - *eax = 0;
> + *eax = env->features[FEAT_6_EAX];
> *ebx = 0;
> *ecx = 0;
> *edx = 0;
> diff --git a/target-i386/cpu.h b/target-i386/cpu.h
> index 4ee12ca..800158e 100644
> --- a/target-i386/cpu.h
> +++ b/target-i386/cpu.h
> @@ -412,6 +412,7 @@ typedef enum FeatureWord {
> FEAT_KVM, /* CPUID[4000_0001].EAX (KVM_CPUID_FEATURES) */
> FEAT_SVM, /* CPUID[8000_000A].EDX */
> FEAT_XSAVE, /* CPUID[EAX=0xd,ECX=1].EAX */
> + FEAT_6_EAX, /* CPUID[6].EAX */
> FEATURE_WORDS,
> } FeatureWord;
>
> @@ -577,6 +578,8 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS];
> #define CPUID_XSAVE_XGETBV1 (1U << 2)
> #define CPUID_XSAVE_XSAVES (1U << 3)
>
> +#define CPUID_6_EAX_ARAT (1U << 2)
> +
> /* CPUID[0x80000007].EDX flags: */
> #define CPUID_APM_INVTSC (1U << 8)
>
> diff --git a/target-i386/kvm.c b/target-i386/kvm.c
> index a26d25a..b786359 100644
> --- a/target-i386/kvm.c
> +++ b/target-i386/kvm.c
> @@ -233,6 +233,8 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s,
> uint32_t function,
> if (!kvm_irqchip_in_kernel()) {
> ret &= ~CPUID_EXT_X2APIC;
> }
> + } else if (function == 6 && reg == R_EAX) {
> + ret |= CPUID_6_EAX_ARAT; /* safe to allow because of emulated APIC */
> } else if (function == 0x80000001 && reg == R_EDX) {
> /* On Intel, kvm returns cpuid according to the Intel spec,
> * so add missing bits according to the AMD spec:
>