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Re: [Qemu-devel] [PATCH 1/2] i386: define the AMD 'amd-ssbd' CPUID featu
From: |
Daniel P . Berrangé |
Subject: |
Re: [Qemu-devel] [PATCH 1/2] i386: define the AMD 'amd-ssbd' CPUID feature bit |
Date: |
Mon, 4 Jun 2018 09:54:40 +0100 |
User-agent: |
Mutt/1.9.5 (2018-04-13) |
On Fri, Jun 01, 2018 at 11:38:08AM -0400, Konrad Rzeszutek Wilk wrote:
> AMD future CPUs expose _two_ ways to utilize the Intel equivalant
> of the Speculative Store Bypass Disable. The first is via
> the virtualized VIRT_SPEC CTRL MSR (0xC001_011f) and the second
> is via the SPEC_CTRL MSR (0x48). The document titled:
> 124441_AMD64_SpeculativeStoreBypassDisable_Whitepaper_final.pdf
>
> gives priority of SPEC CTRL MSR over the VIRT SPEC CTRL MSR.
>
> A copy of this document is available at
> https://bugzilla.kernel.org/show_bug.cgi?id=199889
>
> Anyhow, this means that on future AMD CPUs there will be _two_ ways to
> deal with SSBD.
Oh what fun ;-)
Unless I'm mistaken the current Linux kernel doesn't know about these
new amd-ssbd / amd-no-ssb flags either. Will you also be sending patches
for that half of the problem ?
>
> Signed-off-by: Konrad Rzeszutek Wilk <address@hidden>
> ---
> target/i386/cpu.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 52d334a..f91990c 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -490,7 +490,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] =
> {
> "ibpb", NULL, NULL, NULL,
> NULL, NULL, NULL, NULL,
> NULL, NULL, NULL, NULL,
> - NULL, "virt-ssbd", NULL, NULL,
> + "amd-ssbd", "virt-ssbd", NULL, NULL,
> NULL, NULL, NULL, NULL,
> },
> .cpuid_eax = 0x80000008,
> --
> 1.8.3.1
>
>
Regards,
Daniel
--
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- [Qemu-devel] [PATCH QEMU] Patches for new AMD CPU bits., Konrad Rzeszutek Wilk, 2018/06/01
- [Qemu-devel] [PATCH 1/2] i386: define the AMD 'amd-ssbd' CPUID feature bit, Konrad Rzeszutek Wilk, 2018/06/01
- Re: [Qemu-devel] [PATCH 1/2] i386: define the AMD 'amd-ssbd' CPUID feature bit,
Daniel P . Berrangé <=
- Re: [Qemu-devel] [PATCH 1/2] i386: define the AMD 'amd-ssbd' CPUID feature bit, Eduardo Habkost, 2018/06/04
- Re: [Qemu-devel] [PATCH 1/2] i386: define the AMD 'amd-ssbd' CPUID feature bit, Daniel P . Berrangé, 2018/06/13
- Re: [Qemu-devel] [PATCH 1/2] i386: define the AMD 'amd-ssbd' CPUID feature bit, Konrad Rzeszutek Wilk, 2018/06/13
- Re: [Qemu-devel] [PATCH 1/2] i386: define the AMD 'amd-ssbd' CPUID feature bit, Daniel P . Berrangé, 2018/06/13
- Re: [Qemu-devel] [PATCH 1/2] i386: define the AMD 'amd-ssbd' CPUID feature bit, Konrad Rzeszutek Wilk, 2018/06/13
- Re: [Qemu-devel] [PATCH 1/2] i386: define the AMD 'amd-ssbd' CPUID feature bit, Daniel P . Berrangé, 2018/06/13