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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id f9sm9946119edm.6.2021.02.02.03.03.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 02 Feb 2021 03:03:15 -0800 (PST) Subject: Re: [PATCH] target/i386: Add bus lock debug exception support To: Chenyi Qiang , Richard Henderson , Eduardo Habkost , Xiaoyao Li References: <20210202090224.13274-1-chenyi.qiang@intel.com> From: Paolo Bonzini Message-ID: <7aad62b9-d455-bf30-bea3-187a20578038@redhat.com> Date: Tue, 2 Feb 2021 12:03:13 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210202090224.13274-1-chenyi.qiang@intel.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.351, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 02/02/21 10:02, Chenyi Qiang wrote: > Bus lock debug exception is a feature that can notify the kernel by > generate an #DB trap after the instruction acquires a bus lock when > CPL>0. This allows the kernel to enforce user application throttling or > mitigations. > > This feature is enumerated via CPUID.(EAX=7,ECX=0).ECX[bit 24]. > > Signed-off-by: Chenyi Qiang > --- > target/i386/cpu.c | 2 +- > target/i386/cpu.h | 2 ++ > 2 files changed, 3 insertions(+), 1 deletion(-) > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > index ae89024d36..55f3b5829f 100644 > --- a/target/i386/cpu.c > +++ b/target/i386/cpu.c > @@ -963,7 +963,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = { > "avx512bitalg", NULL, "avx512-vpopcntdq", NULL, > "la57", NULL, NULL, NULL, > NULL, NULL, "rdpid", NULL, > - NULL, "cldemote", NULL, "movdiri", > + "bus-lock-detect", "cldemote", NULL, "movdiri", > "movdir64b", NULL, NULL, NULL, > }, > .cpuid = { > diff --git a/target/i386/cpu.h b/target/i386/cpu.h > index d23a5b340a..417f49b721 100644 > --- a/target/i386/cpu.h > +++ b/target/i386/cpu.h > @@ -762,6 +762,8 @@ typedef uint64_t FeatureWordArray[FEATURE_WORDS]; > #define CPUID_7_0_ECX_LA57 (1U << 16) > /* Read Processor ID */ > #define CPUID_7_0_ECX_RDPID (1U << 22) > +/* Bus Lock Debug Exception */ > +#define CPUID_7_0_ECX_BUS_LOCK_DETECT (1U << 24) > /* Cache Line Demote Instruction */ > #define CPUID_7_0_ECX_CLDEMOTE (1U << 25) > /* Move Doubleword as Direct Store Instruction */ > Queued, thanks. Paolo