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[31.46.240.76]) by smtp.gmail.com with ESMTPSA id b11-20020a05600c4e0b00b004140837a0d4sm680841wmq.3.2024.03.21.12.26.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Mar 2024 12:26:44 -0700 (PDT) Sender: Ingo Molnar Date: Thu, 21 Mar 2024 20:26:42 +0100 From: Ingo Molnar To: Borislav Petkov Cc: X86 ML , LKML , Boris Ostrovsky , "Maciej S. Szmigiero" Subject: Re: [PATCH 2/2] x86/CPU/AMD: Improve the erratum 1386 workaround Message-ID: References: <20240321120548.22687-1-bp@alien8.de> <20240321120548.22687-2-bp@alien8.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240321120548.22687-2-bp@alien8.de> * Borislav Petkov wrote: > From: "Borislav Petkov (AMD)" > > Disable XSAVES only on machines which haven't loaded the microcode > revision containing the erratum fix. > > This will come in handy when running archaic OSes as guests. OSes whose > brilliant programmers thought that CPUID is overrated and one should not > query it but use features directly, ala shoot first, ask questions > later... but only if you're alive after the shooting. > > Signed-off-by: Borislav Petkov (AMD) > Cc: Boris Ostrovsky > Cc: "Maciej S. Szmigiero" > --- > arch/x86/kernel/cpu/amd.c | 28 ++++++++++++++++++++++++++++ > 1 file changed, 28 insertions(+) > > diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c > index 6d8677e80ddb..c02b07feff6e 100644 > --- a/arch/x86/kernel/cpu/amd.c > +++ b/arch/x86/kernel/cpu/amd.c > @@ -15,6 +15,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -804,6 +805,16 @@ static void init_amd_bd(struct cpuinfo_x86 *c) > > static void fix_erratum_1386(struct cpuinfo_x86 *c) > { > + u8 fam, model, stpng, rev; > + union zen_patch_rev p; > + > + p.ucode_rev = c->microcode; > + > + fam = p.ext_fam + 0xf; > + model = p.ext_model << 4 | p.model; > + stpng = p.stepping; Please make this 'stepping' - we don't have a single 'stpng' variable name in the kernel currently, and that's very good so. Thanks, Ingo