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[46.139.12.213]) by smtp.gmail.com with ESMTPSA id y184-v6sm11201974wmg.17.2018.10.02.02.27.33 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 02 Oct 2018 02:27:34 -0700 (PDT) Date: Tue, 2 Oct 2018 11:27:31 +0200 From: Ingo Molnar To: Tim Chen Cc: Jiri Kosina , Thomas Gleixner , Thomas Lendacky , Ingo Molnar , Peter Zijlstra , Josh Poimboeuf , Andrea Arcangeli , David Woodhouse , Andi Kleen , Dave Hansen , Casey Schaufler , Asit Mallick , Arjan van de Ven , Jon Masters , linux-kernel@vger.kernel.org, x86@kernel.org Subject: Re: [Patch v2 3/4] x86/speculation: Extend per process STIBP to AMD cpus. Message-ID: <20181002092731.GB122128@gmail.com> References: <705b51cba5b5e7805aeb08af7f7d21e6ec897a17.1537920575.git.tim.c.chen@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <705b51cba5b5e7805aeb08af7f7d21e6ec897a17.1537920575.git.tim.c.chen@linux.intel.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Tim Chen wrote: > From: Thomas Lendacky > > We extend the app to app spectre v2 mitigation using STIBP > to the AMD cpus. We need to take care of special s/to the AMD cpus /to AMD CPUs > cases for AMD cpu's update of SPEC_CTRL MSR to avoid double > writing of MSRs from update to SSBD and STIBP. s/AMD cpu /AMD CPU > > Originally-by: Thomas Lendacky > Signed-off-by: Tim Chen > --- > arch/x86/kernel/process.c | 48 +++++++++++++++++++++++++++++++++++++---------- > 1 file changed, 38 insertions(+), 10 deletions(-) > > diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c > index cb24014..4a3a672 100644 > --- a/arch/x86/kernel/process.c > +++ b/arch/x86/kernel/process.c > @@ -399,6 +399,10 @@ static __always_inline void set_spec_ctrl_state(unsigned long tifn) > { > u64 msr = x86_spec_ctrl_base; > > + /* > + * AMD cpu may have used a different method to update SSBD, so > + * we need to be sure we are using the SPEC_CTRL MSR for SSBD. s/AMD cpu may have used a different method to update SSBD /AMD CPUs may use a different method to update the SSBD Thanks, Ingo