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([2001:b07:6468:f312:63a7:c72e:ea0e:6045]) by smtp.googlemail.com with ESMTPSA id dc23-20020a056402311700b005525a9abf73sm171094edb.11.2023.12.13.09.40.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 Dec 2023 09:40:51 -0800 (PST) Message-ID: <13d72960-c7bc-4bc2-8404-931d3de04ecf@redhat.com> Date: Wed, 13 Dec 2023 18:40:47 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v10 03/50] KVM: SEV: Do not intercept accesses to MSR_IA32_XSS for SEV-ES guests To: Sean Christopherson Cc: Michael Roth , kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-crypto@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, jroedel@suse.de, thomas.lendacky@amd.com, hpa@zytor.com, ardb@kernel.org, vkuznets@redhat.com, jmattson@google.com, luto@kernel.org, dave.hansen@linux.intel.com, slp@redhat.com, pgonda@google.com, peterz@infradead.org, srinivas.pandruvada@linux.intel.com, rientjes@google.com, dovmurik@linux.ibm.com, tobin@ibm.com, bp@alien8.de, vbabka@suse.cz, kirill@shutemov.name, ak@linux.intel.com, tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com, alpergun@google.com, jarkko@kernel.org, ashish.kalra@amd.com, nikunj.dadhania@amd.com, pankaj.gupta@amd.com, liam.merwick@oracle.com, zhi.a.wang@intel.com, Alexey Kardashevskiy References: <20231016132819.1002933-1-michael.roth@amd.com> <20231016132819.1002933-4-michael.roth@amd.com> From: Paolo Bonzini Autocrypt: addr=pbonzini@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 8F51C40004 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: wqq5mja4zjzwfhj4abbg9yfxucx9fhgf X-HE-Tag: 1702489256-34528 X-HE-Meta: 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 bAZ+i/u3 cEynuEbhJEvhWCG+hu3pA2AgQzJw+ji/5yaeF9vSDOrrsARNoSKBLXK96UrmJZprjoa9QHFjW8aTgD/Frui1fO5UPLV2JyryFy4D5/mtHRAI5CgESulW7xSL72BueyXKXi5gPLtlQvwn1aTRr8wsmZWRq+15wSP16o3Xzk/0Cb40iicco4fyCMqw1xd9r1e04VLGqGkyQNYOkr4OJtcZ9pR7dnBRhvr3CF+2Ft6eWZQoutPbe60E1OMPIXoQvqTVpFwD+AV2uOSQA+gGepidnbS4zHzmWPv/eYxiwBjQ/dLAPaubEf+vthhv//YY8fXTaOApwg9REpBeDp/5X/L8tgRXl8Il+di/JqdBgBgpjmBfUGOSdAJouHJYo7E4x7Q+RnCP4YGHeD3bPTQhUHkMUJ4wBZLRzg8rCoKHGzLjnyyJJP5f2h5jzLkcoOg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000134, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 12/13/23 18:30, Sean Christopherson wrote: >> For now, all we can do is document our wishes, with which userspace had >> better comply. Please send a patch to QEMU that makes it obey. > Discussed this early today with Paolo at PUCK and pointed out that (a) the CPU > context switches the underlying state, (b) SVM doesn't allow intercepting*just* > XSAVES, and (c) SNP's AP creation can bypass XSS interception. > > So while we all (all == KVM folks) agree that this is rather terrifying, e.g. > gives KVM zero option if there is a hardware issue, it's "fine" to let the guest > use XSAVES/XSS. Indeed; looks like I've got to queue this for 6.7 after all. Paolo