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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.googlemail.com with ESMTPSA id b13-20020aa7d48d000000b00418d53c61acsm1299643edr.85.2022.03.16.10.20.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 16 Mar 2022 10:20:03 -0700 (PDT) Message-ID: <19c431c2-283b-b483-6bd1-6817e483eb3a@redhat.com> Date: Wed, 16 Mar 2022 18:20:02 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PULL 15/22] x86: Grant AMX permission for guest Content-Language: en-US To: =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= , Peter Krempa References: <20220308113445.859669-1-pbonzini@redhat.com> <20220308113445.859669-16-pbonzini@redhat.com> From: Paolo Bonzini In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Host-Lookup-Failed: Reverse DNS lookup failed for 2a00:1450:4864:20::533 (failed) Received-SPF: pass client-ip=2a00:1450:4864:20::533; envelope-from=paolo.bonzini@gmail.com; helo=mail-ed1-x533.google.com X-Spam_score_int: 0 X-Spam_score: -0.1 X-Spam_bar: / X-Spam_report: (-0.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FORGED_FROMDOMAIN=0.249, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.249, NICE_REPLY_A=-0.001, PDS_HP_HELO_NORDNS=0.659, RCVD_IN_DNSWL_NONE=-0.0001, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Yang Zhong , qemu-devel@nongnu.org, Jing Liu Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 3/16/22 17:05, Daniel P. Berrangé wrote: > On Wed, Mar 16, 2022 at 04:57:39PM +0100, Peter Krempa wrote: >> On Tue, Mar 08, 2022 at 12:34:38 +0100, Paolo Bonzini wrote: >>> From: Yang Zhong >>> >>> Kernel allocates 4K xstate buffer by default. For XSAVE features >>> which require large state component (e.g. AMX), Linux kernel >>> dynamically expands the xstate buffer only after the process has >>> acquired the necessary permissions. Those are called dynamically- >>> enabled XSAVE features (or dynamic xfeatures). >>> >>> There are separate permissions for native tasks and guests. >>> >>> Qemu should request the guest permissions for dynamic xfeatures >>> which will be exposed to the guest. This only needs to be done >>> once before the first vcpu is created. >>> >>> KVM implemented one new ARCH_GET_XCOMP_SUPP system attribute API to >>> get host side supported_xcr0 and Qemu can decide if it can request >>> dynamically enabled XSAVE features permission. >>> https://lore.kernel.org/all/20220126152210.3044876-1-pbonzini@redhat.com/ >>> >>> Suggested-by: Paolo Bonzini >>> Signed-off-by: Yang Zhong >>> Signed-off-by: Jing Liu >>> Message-Id: <20220217060434.52460-4-yang.zhong@intel.com> >>> Signed-off-by: Paolo Bonzini >>> --- >>> target/i386/cpu.c | 7 +++++ >>> target/i386/cpu.h | 4 +++ >>> target/i386/kvm/kvm-cpu.c | 12 ++++---- >>> target/i386/kvm/kvm.c | 57 ++++++++++++++++++++++++++++++++++++++ >>> target/i386/kvm/kvm_i386.h | 1 + >>> 5 files changed, 75 insertions(+), 6 deletions(-) >> >> With this commit qemu crashes for me when invoking the following >> QMP command: > > It is way worse than that even. If you remove '-S' you get an > immediate kaboom on startup on AMD hosts > > $ ./build/qemu-system-x86_64 -accel kvm > Unable to init server: Could not connect: Connection refused > qemu-system-x86_64: ../target/i386/kvm/kvm-cpu.c:105: kvm_cpu_xsave_init: Assertion `esa->size == eax' failed. > Aborted (core dumped) I'll check it tomorrow, thanks. Paolo