From: Sean Christopherson <seanjc@google.com>
To: Michael Roth <michael.roth@amd.com>
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 <brijesh.singh@amd.com>
Subject: Re: [PATCH v14 03/22] KVM: SEV: Add GHCB handling for Hypervisor Feature Support requests
Date: Thu, 25 Apr 2024 14:55:25 -0700 [thread overview]
Message-ID: <ZirRTVebhn-W8w7W@google.com> (raw)
In-Reply-To: <20240425205245.aga3cyo5qa5xfnee@amd.com>
On Thu, Apr 25, 2024, Michael Roth wrote:
> On Wed, Apr 24, 2024 at 01:21:49PM -0700, Sean Christopherson wrote:
> > 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.
> >
>
> The requirements for implementing the non-SNP aspects of the GHCB
> version 2 protocol are fairly minimal, and KVM_SEV_INIT2 is already
> migration incompatible with older kernels running KVM_SEV_ES_INIT (e.g.
> migrate to newer host, shutdown, start -> measurement failure). There
> are QEMU patches here that allow for controlling this via QEMU versioned
> machine types to handle this [1]
>
> So I think it makes sense to go ahead move to GHCB version 2 as the base
> version for all SEV-ES/SNP guests created via KVM_SEV_INIT2, and leave
> KVM_SEV_ES_INIT restricted to GHCB version 1.
Hmm, I like that. Dangle a carrot to get folks to switch to KVM_SEV_INIT2.
> This could be done in a pretty self-contained way for SEV-ES by applying
> the following patches from this series which are the version 2 protocol
> interfaces also applicable to SEV-ES:
>
> KVM: SEV: Add GHCB handling for Hypervisor Feature Support requests
> KVM: SEV: Add support to handle AP reset MSR protocol
> KVM: SEV: Add support for GHCB-based termination requests
>
> And then applying the below patch on top to set GHCB version 1 or 2
> accordingly for SEV-ES. (and relocating the GHCB_VERSION_MAX bump to the
> below patch as well, although it's not really used at that point so
> could also just be dropped completely).
>
> Then in the future we can extend KVM_SEV_INIT2 to allow specifying
> specific/newer versions of the GHCB protocol when that becomes needed.
Any reason not to let userspace restrict the GHCB protocol from the get-go? It
seems inevitable that KVM will need to support that at some point, we'd have a
wee bit more confidence that we didn't botch the definition of KVM_SEV_INIT2 and
end up with KVM_SEV_INIT3, and in the unlikely event some poor provider gets into
a situation where guests are crashing because they don't handle v2 correctly,
userspace can workaround the issue without need to extend KVM's uAPI.
> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> index 28140bc8af27..229cb630b540 100644
> --- a/arch/x86/kvm/svm/svm.h
> +++ b/arch/x86/kvm/svm/svm.h
> @@ -87,6 +87,7 @@ struct kvm_sev_info {
> struct list_head regions_list; /* List of registered regions */
> u64 ap_jump_table; /* SEV-ES AP Jump Table address */
> u64 vmsa_features;
> + u64 ghcb_version; /* Highest guest GHCB protocol version allowed */
This can/should be a u16, no?
> struct kvm *enc_context_owner; /* Owner of copied encryption context */
> struct list_head mirror_vms; /* List of VMs mirroring */
> struct list_head mirror_entry; /* Use as a list entry of mirrors */
next prev parent reply other threads:[~2024-04-25 21:55 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-21 18:01 [PATCH v14 00/22] Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support Michael Roth
2024-04-21 18:01 ` [PATCH v14 01/22] KVM: SEV: Select KVM_GENERIC_PRIVATE_MEM when CONFIG_KVM_AMD_SEV=y Michael Roth
2024-04-21 18:01 ` [PATCH v14 02/22] KVM: SEV: Add support to handle AP reset MSR protocol Michael Roth
2024-04-21 18:01 ` [PATCH v14 03/22] KVM: SEV: Add GHCB handling for Hypervisor Feature Support requests Michael Roth
2024-04-24 20:21 ` Sean Christopherson
2024-04-25 20:52 ` Michael Roth
2024-04-25 21:55 ` Sean Christopherson [this message]
2024-04-21 18:01 ` [PATCH v14 04/22] KVM: SEV: Add initial SEV-SNP support Michael Roth
2024-04-21 18:01 ` [PATCH v14 05/22] KVM: SEV: Add KVM_SEV_SNP_LAUNCH_START command Michael Roth
2024-04-24 23:26 ` Sean Christopherson
2024-04-21 18:01 ` [PATCH v14 06/22] KVM: SEV: Add KVM_SEV_SNP_LAUNCH_UPDATE command Michael Roth
2024-04-24 23:58 ` Sean Christopherson
2024-04-21 18:01 ` [PATCH v14 07/22] KVM: SEV: Add KVM_SEV_SNP_LAUNCH_FINISH command Michael Roth
2024-04-21 18:01 ` [PATCH v14 08/22] KVM: SEV: Add support to handle GHCB GPA register VMGEXIT Michael Roth
2024-04-21 18:01 ` [PATCH v14 09/22] KVM: SEV: Add support to handle MSR based Page State Change VMGEXIT Michael Roth
2024-04-24 20:59 ` Sean Christopherson
2024-04-25 22:00 ` Michael Roth
2024-04-25 22:13 ` Sean Christopherson
2024-04-26 17:16 ` Michael Roth
2024-04-26 20:14 ` Sean Christopherson
2024-04-26 22:24 ` Michael Roth
2024-04-26 22:48 ` Michael Roth
2024-04-21 18:01 ` [PATCH v14 10/22] KVM: SEV: Add support to handle " Michael Roth
2024-04-21 18:01 ` [PATCH v14 11/22] KVM: SEV: Add support to handle RMP nested page faults Michael Roth
2024-04-21 18:01 ` [PATCH v14 12/22] KVM: SEV: Support SEV-SNP AP Creation NAE event Michael Roth
2024-04-21 18:01 ` [PATCH v14 13/22] KVM: SEV: Add support for GHCB-based termination requests Michael Roth
2024-04-21 18:01 ` [PATCH v14 14/22] KVM: SEV: Implement gmem hook for initializing private pages Michael Roth
2024-04-21 18:01 ` [PATCH v14 15/22] KVM: SEV: Implement gmem hook for invalidating " Michael Roth
2024-04-21 18:01 ` [PATCH v14 16/22] KVM: x86: Implement gmem hook for determining max NPT mapping level Michael Roth
2024-04-25 0:45 ` Sean Christopherson
2024-04-21 18:01 ` [PATCH v14 17/22] KVM: SEV: Avoid WBINVD for HVA-based MMU notifications for SNP Michael Roth
2024-04-25 0:17 ` Sean Christopherson
2024-04-21 18:01 ` [PATCH v14 18/22] KVM: SVM: Add module parameter to enable SEV-SNP Michael Roth
2024-04-21 18:01 ` [PATCH v14 19/22] KVM: SEV: Provide support for SNP_GUEST_REQUEST NAE event Michael Roth
2024-04-21 18:01 ` [PATCH v14 20/22] crypto: ccp: Add the SNP_VLEK_LOAD command Michael Roth
2024-04-21 18:01 ` [PATCH v14 21/22] crypto: ccp: Add the SNP_{PAUSE,RESUME}_ATTESTATION commands Michael Roth
2024-04-25 0:15 ` Sean Christopherson
2024-04-26 17:35 ` Michael Roth
2024-04-26 19:57 ` Sean Christopherson
2024-04-26 21:46 ` Michael Roth
2024-04-27 0:10 ` Sean Christopherson
2024-04-27 1:32 ` Michael Roth
2024-04-29 14:27 ` Sean Christopherson
2024-04-21 18:01 ` [PATCH v14 22/22] KVM: SEV: Provide support for SNP_EXTENDED_GUEST_REQUEST NAE event Michael Roth
2024-04-25 0:10 ` Sean Christopherson
2024-04-26 17:57 ` Michael Roth
2024-04-23 16:21 ` [PATCH v14 23/22] [SQUASH] KVM: SEV: Add support to handle GHCB GPA register VMGEXIT Michael Roth
2024-04-23 16:21 ` [PATCH v14 24/22] [SQUASH] KVM: SEV: Add support to handle MSR based Page State Change VMGEXIT Michael Roth
2024-04-23 16:21 ` [PATCH v14 25/22] [SQUASH] KVM: SEV: Add support to handle " Michael Roth
2024-04-23 16:21 ` [PATCH v14 26/22] [SQUASH] KVM: SEV: Add support for GHCB-based termination requests Michael Roth
2024-04-23 16:21 ` [PATCH v14 27/22] [SQUASH] KVM: SEV: Provide support for SNP_GUEST_REQUEST NAE event Michael Roth
2024-04-23 16:21 ` [PATCH v14 28/22] [SQUASH] KVM: SEV: Provide support for SNP_EXTENDED_GUEST_REQUEST " Michael Roth
2024-04-23 21:36 ` Jarkko Sakkinen
2024-04-23 16:21 ` [PATCH v14 29/22] [SQUASH] KVM: SEV: Support SEV-SNP AP Creation " Michael Roth
2024-04-23 16:31 ` [PATCH v14 00/22] Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support Michael Roth
2024-04-24 16:51 ` Paolo Bonzini
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