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Re: [Qemu-devel] [PATCH] i386: forward CPUID cache leaves when -cpu host
From: |
Andreas Färber |
Subject: |
Re: [Qemu-devel] [PATCH] i386: forward CPUID cache leaves when -cpu host is used |
Date: |
Mon, 02 Sep 2013 14:55:36 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130801 Thunderbird/17.0.8 |
Hi,
"target-i386:" please.
Am 27.08.2013 22:38, schrieb Benoît Canet:
> Some users running cpu intensive tasks checking the cache CPUID leaves at
> startup and making decisions based on the result reported that the guest was
> not reflecting the host CPUID leaves when -cpu host is used.
>
> This patch fix this.
>
> Signed-off-by: Benoit Canet <address@hidden>
> ---
> target-i386/cpu.c | 19 +++++++++++++++++++
> target-i386/cpu.h | 1 +
> 2 files changed, 20 insertions(+)
>
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index 42c5de0..2c8eaf7 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -374,6 +374,7 @@ typedef struct x86_def_t {
> int stepping;
> FeatureWordArray features;
> char model_id[48];
> + bool fwd_cpuid_cache_leaves;
> } x86_def_t;
>
> #define I486_FEATURES (CPUID_FP87 | CPUID_VME | CPUID_PSE)
> @@ -1027,6 +1028,7 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def)
> assert(kvm_enabled());
>
> x86_cpu_def->name = "host";
> + x86_cpu_def->fwd_cpuid_cache_leaves = true;
> host_cpuid(0x0, 0, &eax, &ebx, &ecx, &edx);
> x86_cpu_vendor_words2str(x86_cpu_def->vendor, ebx, edx, ecx);
>
> @@ -1776,6 +1778,7 @@ static void cpu_x86_register(X86CPU *cpu, const char
> *name, Error **errp)
> env->features[FEAT_C000_0001_EDX] = def->features[FEAT_C000_0001_EDX];
> env->features[FEAT_7_0_EBX] = def->features[FEAT_7_0_EBX];
> env->cpuid_xlevel2 = def->xlevel2;
> + env->fwd_cpuid_cache_leaves = def->fwd_cpuid_cache_leaves;
>
> object_property_set_str(OBJECT(cpu), def->model_id, "model-id", errp);
> }
> @@ -1949,6 +1952,10 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
> uint32_t count,
> }
> break;
> case 2:
> + if (env->fwd_cpuid_cache_leaves) {
> + host_cpuid(0x2, 0, eax, ebx, ecx, edx);
> + break;
> + }
> /* cache info: needed for Pentium Pro compatibility */
> *eax = 1;
> *ebx = 0;
> @@ -1956,6 +1963,10 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
> uint32_t count,
> *edx = 0x2c307d;
> break;
> case 4:
> + if (env->fwd_cpuid_cache_leaves) {
> + host_cpuid(0x4, count, eax, ebx, ecx, edx);
> + break;
> + }
> /* cache info: needed for Core compatibility */
> if (cs->nr_cores > 1) {
> *eax = (cs->nr_cores - 1) << 26;
> @@ -2102,6 +2113,10 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
> uint32_t count,
> break;
> case 0x80000005:
> /* cache info (L1 cache) */
> + if (env->fwd_cpuid_cache_leaves) {
> + host_cpuid(0x80000005, 0, eax, ebx, ecx, edx);
> + break;
> + }
> *eax = 0x01ff01ff;
> *ebx = 0x01ff01ff;
> *ecx = 0x40020140;
> @@ -2109,6 +2124,10 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
> uint32_t count,
> break;
> case 0x80000006:
> /* cache info (L2 cache) */
> + if (env->fwd_cpuid_cache_leaves) {
> + host_cpuid(0x80000006, 0, eax, ebx, ecx, edx);
> + break;
> + }
> *eax = 0;
> *ebx = 0x42004200;
> *ecx = 0x02008140;
This hunk may trivially conflict with Eduardo's cache flags cleanup.
> diff --git a/target-i386/cpu.h b/target-i386/cpu.h
> index 8a3d0fd..1ec32fa 100644
> --- a/target-i386/cpu.h
> +++ b/target-i386/cpu.h
> @@ -865,6 +865,7 @@ typedef struct CPUX86State {
> bool tsc_valid;
> int tsc_khz;
> void *kvm_xsave_buf;
> + bool fwd_cpuid_cache_leaves;
>
> /* in order to simplify APIC support, we leave this pointer to the
> user */
Please place the field in X86CPU instead and document it.
Otherwise patch looks okay to me on a brief sight; but since this is
about -cpu host I would prefer this to go through uq/master once fixed
or at least to get some acks.
Regards,
Andreas
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- Re: [Qemu-devel] [PATCH] i386: forward CPUID cache leaves when -cpu host is used,
Andreas Färber <=