On Thu, Sep 19, 2024 at 01:10:11PM +0800, Chao Gao wrote:
> Date: Thu, 19 Sep 2024 13:10:11 +0800
> From: Chao Gao <chao....@intel.com>
> Subject: [PATCH] target/i386: Add more features enumerated by CPUID.7.2.EDX
> X-Mailer: git-send-email 2.46.1
>
> Following 5 bits in CPUID.7.2.EDX are supported by KVM. Add their
> supports in QEMU. Each of them indicates certain bits of IA32_SPEC_CTRL
> are supported. Those bits can control CPU speculation behavior which can
> be used to defend against side-channel attacks.
>
> bit0: intel-psfd
> if 1, indicates bit 7 of the IA32_SPEC_CTRL MSR is supported. Bit 7 of
> this MSR disables Fast Store Forwarding Predictor without disabling
> Speculative Store Bypass
>
> bit1: ipred-ctrl
> If 1, indicates bits 3 and 4 of the IA32_SPEC_CTRL MSR are supported.
> Bit 3 of this MSR enables IPRED_DIS control for CPL3. Bit 4 of this
> MSR enables IPRED_DIS control for CPL0/1/2
>
> bit2: rrsba-ctrl
> If 1, indicates bits 5 and 6 of the IA32_SPEC_CTRL MSR are supported.
> Bit 5 of this MSR disables RRSBA behavior for CPL3. Bit 6 of this MSR
> disables RRSBA behavior for CPL0/1/2
>
> bit3: ddpd-u
> If 1, indicates bit 8 of the IA32_SPEC_CTRL MSR is supported. Bit 8 of
> this MSR disables Data Dependent Prefetcher.
>
> bit4: bhi-ctrl
> if 1, indicates bit 10 of the IA32_SPEC_CTRL MSR is supported. Bit 10
> of this MSR enables BHI_DIS_S behavior.
>
> Signed-off-by: Chao Gao <chao....@intel.com>
> ---
> target/i386/cpu.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 85ef7452c0..18ba958f46 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -1148,8 +1148,8 @@ FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
> [FEAT_7_2_EDX] = {
> .type = CPUID_FEATURE_WORD,
> .feat_names = {
> - NULL, NULL, NULL, NULL,
> - NULL, "mcdt-no", NULL, NULL,
> + "intel-psfd", "ipred-ctrl", "rrsba-ctrl", "ddpd-u",
> + "bhi-ctrl", "mcdt-no", NULL, NULL,
IIUC, these bits depend on "spec-ctrl", which indicates the presence of
IA32_SPEC_CTRL.
Then I think we'd better add dependencies in feature_dependencies[].
-Zhao
> NULL, NULL, NULL, NULL,
> NULL, NULL, NULL, NULL,
> NULL, NULL, NULL, NULL,
> --
> 2.46.1
>
>
