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AJvYcCXAJBZw3nkSmVZLvHhyokSoPSZxpapOXnSSDeJv2N/uMEUCrJDwgNBInq4CtSXoMVBJm5hePEEh1+XjXagBEkA6EdCCwVFPyUPJMA== X-Gm-Message-State: AOJu0Yw14Vtg2pCGXqUVAwG3efF4NEgD4WVbl+RfhcnWImv6BdpEEzzK x78fBNjD+K2RCNFMYCBO/s+1sF560xk9n3Y4Tng910+fsV/3kxj9PcyZQSNxLls3OaLOuVqANpC 0+w== X-Google-Smtp-Source: AGHT+IET29Be+TqLLxR1el2WX7B1TltJHuVLHw4XBc2UEobX1IG760KHrKW5Mr9mGqY0ZbBfjntc+5CKv7o= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:c54c:0:b0:de1:d49:7ff6 with SMTP id v73-20020a25c54c000000b00de10d497ff6mr385878ybe.7.1713990111258; Wed, 24 Apr 2024 13:21:51 -0700 (PDT) Date: Wed, 24 Apr 2024 13:21:49 -0700 In-Reply-To: <20240421180122.1650812-4-michael.roth@amd.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240421180122.1650812-1-michael.roth@amd.com> <20240421180122.1650812-4-michael.roth@amd.com> Message-ID: Subject: Re: [PATCH v14 03/22] KVM: SEV: Add GHCB handling for Hypervisor Feature Support requests From: Sean Christopherson To: Michael Roth Cc: 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, pbonzini@redhat.com, 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, 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, Brijesh Singh Content-Type: text/plain; charset="us-ascii" On Sun, Apr 21, 2024, Michael Roth wrote: > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index 6e31cb408dd8..1d2264e93afe 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -33,9 +33,11 @@ > #include "cpuid.h" > #include "trace.h" > > -#define GHCB_VERSION_MAX 1ULL > +#define GHCB_VERSION_MAX 2ULL > #define GHCB_VERSION_MIN 1ULL This needs a userspace control. Being unable to limit the GHCB version advertised to the guest is going to break live migration of SEV-ES VMs, e.g. if a pool of hosts has some kernels running this flavor of KVM, and some hosts running an older KVM that doesn't support v2.