From: Brijesh Singh <brijesh.singh@amd.com>
To: Sean Christopherson <seanjc@google.com>
Cc: brijesh.singh@amd.com, Peter Gonda <pgonda@google.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
kvm list <kvm@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>,
jroedel@suse.de, "Lendacky, Thomas" <thomas.lendacky@amd.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@intel.com>,
David Rientjes <rientjes@google.com>,
peterz@infradead.org, "H. Peter Anvin" <hpa@zytor.com>,
tony.luck@intel.com
Subject: Re: [PATCH Part2 RFC v2 36/37] KVM: SVM: Provide support for SNP_GUEST_REQUEST NAE event
Date: Tue, 11 May 2021 13:34:48 -0500 [thread overview]
Message-ID: <07ce14c1-d9b2-2a88-9297-cae4e8dbea1f@amd.com> (raw)
In-Reply-To: <YJmjAaogWeFgCEmb@google.com>
On 5/10/21 4:17 PM, Sean Christopherson wrote:
> On Mon, May 10, 2021, Brijesh Singh wrote:
>> On 5/10/21 1:57 PM, Peter Gonda wrote:
>>>> +e_fail:
>>>> + ghcb_set_sw_exit_info_2(ghcb, rc);
>>>> + return;
>>>> +
>>>> +e_term:
>>>> + ghcb_set_sw_exit_info_1(ghcb, 1);
>>>> + ghcb_set_sw_exit_info_2(ghcb,
>>>> + X86_TRAP_GP |
>>>> + SVM_EVTINJ_TYPE_EXEPT |
>>>> + SVM_EVTINJ_VALID);
>>>> +}
>>> I am probably missing something in the spec but I don't see any
>>> references to #GP in the '4.1.7 SNP Guest Request' section. Why is
>>> this different from e_fail?
>> The spec does not say to inject the #GP, I chose this because guest is
>> not adhering to the spec and there was a not a good error code in the
>> GHCB spec to communicate this condition. Per the spec, both the request
>> and response page must be a valid GPA. If we detect that guest is not
>> following the spec then its a guest BUG. IIRC, other places in the KVM
>> does something similar when guest is trying invalid operation.
> The GHCB spec should be updated to define an error code, even if it's a blanket
> statement for all VMGEXITs that fail to adhere to the spec. Arbitrarily choosing
> an error code and/or exception number makes the information useless to the guest
> because the guest can't take specific action for those failures. E.g. if there
> is a return code specifically for GHCB spec violation, then the guest can panic,
> WARN, etc... knowing that it done messed up.
The GHCB is finalized and released so I don't think it will be covered
in v2. But I will go ahead and file the report so that it is considered
in the next updates. Having said that, I do see that for other commands
(e.g, HV door bell page) the spec spell out that if guest provides an
invalid GPA then inject a #GP. I guess we need to move that statement
and apply to all the commands. Until then I am fine with not injecting
#GP to not divert from the spec.
> "Injecting" an exception is particularly bad, because if the guest kernel takes
> that request literally and emulates a #GP, then we can end up in a situation
> where someone files a bug report because VMGEXIT is hitting a #GP and confusion
> ensues.
next prev parent reply other threads:[~2021-05-11 18:34 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-30 12:37 [PATCH Part2 RFC v2 00/37] Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support Brijesh Singh
2021-04-30 12:37 ` [PATCH Part2 RFC v2 01/37] KVM: SVM: Add support to handle AP reset MSR protocol Brijesh Singh
2021-04-30 12:37 ` [PATCH Part2 RFC v2 02/37] KVM: SVM: Provide the Hypervisor Feature support VMGEXIT Brijesh Singh
2021-04-30 12:37 ` [PATCH Part2 RFC v2 03/37] KVM: SVM: Increase the GHCB protocol version Brijesh Singh
2021-04-30 12:37 ` [PATCH Part2 RFC v2 04/37] x86/cpufeatures: Add SEV-SNP CPU feature Brijesh Singh
2021-04-30 12:37 ` [PATCH Part2 RFC v2 05/37] x86/sev: Add the host SEV-SNP initialization support Brijesh Singh
2021-04-30 12:37 ` [PATCH Part2 RFC v2 06/37] x86/sev: Add RMP entry lookup helpers Brijesh Singh
2021-04-30 12:37 ` [PATCH Part2 RFC v2 07/37] x86/sev: Add helper functions for RMPUPDATE and PSMASH instruction Brijesh Singh
2021-04-30 12:37 ` [PATCH Part2 RFC v2 08/37] x86/sev: Split the physmap when adding the page in RMP table Brijesh Singh
2021-05-03 15:07 ` Peter Zijlstra
2021-05-03 15:15 ` Andy Lutomirski
2021-05-03 15:41 ` Dave Hansen
2021-05-07 11:28 ` Vlastimil Babka
2021-04-30 12:37 ` [PATCH Part2 RFC v2 09/37] x86/traps: Define RMP violation #PF error code Brijesh Singh
2021-04-30 12:37 ` [PATCH Part2 RFC v2 10/37] x86/fault: Add support to handle the RMP fault for kernel address Brijesh Singh
2021-05-03 14:44 ` Dave Hansen
2021-05-03 15:03 ` Andy Lutomirski
2021-05-03 15:49 ` Brijesh Singh
2021-05-03 15:37 ` Brijesh Singh
2021-05-03 16:15 ` Dave Hansen
2021-05-03 17:19 ` Brijesh Singh
2021-05-03 17:31 ` Brijesh Singh
2021-05-03 17:40 ` Andy Lutomirski
2021-05-03 19:41 ` Brijesh Singh
2021-05-03 19:43 ` Dave Hansen
2021-05-04 12:31 ` Brijesh Singh
2021-05-04 14:33 ` Dave Hansen
2021-05-04 15:16 ` Brijesh Singh
2021-04-30 12:37 ` [PATCH Part2 RFC v2 11/37] x86/fault: Add support to handle the RMP fault for user address Brijesh Singh
2021-04-30 12:37 ` [PATCH Part2 RFC v2 12/37] crypto:ccp: Define the SEV-SNP commands Brijesh Singh
2021-04-30 12:37 ` [PATCH Part2 RFC v2 13/37] crypto: ccp: Add support to initialize the AMD-SP for SEV-SNP Brijesh Singh
2021-04-30 12:37 ` [PATCH Part2 RFC v2 14/37] crypto: ccp: Shutdown SNP firmware on kexec Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 15/37] crypto:ccp: Provide APIs to issue SEV-SNP commands Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 16/37] crypto: ccp: Handle the legacy TMR allocation when SNP is enabled Brijesh Singh
2021-05-10 18:23 ` Peter Gonda
2021-05-10 20:07 ` Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 17/37] crypto: ccp: Handle the legacy SEV command " Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 18/37] KVM: SVM: make AVIC backing, VMSA and VMCB memory allocation SNP safe Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 19/37] KVM: SVM: Add initial SEV-SNP support Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 20/37] KVM: SVM: define new SEV_FEATURES field in the VMCB Save State Area Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 21/37] KVM: SVM: Add KVM_SNP_INIT command Brijesh Singh
2021-05-06 20:25 ` Peter Gonda
2021-05-06 22:29 ` Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 22/37] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_START command Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 23/37] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_UPDATE command Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 24/37] KVM: SVM: Reclaim the guest pages when SEV-SNP VM terminates Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 25/37] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_FINISH command Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 26/37] KVM: X86: Add kvm_x86_ops to get the max page level for the TDP Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 27/37] KVM: X86: Introduce kvm_mmu_map_tdp_page() for use by SEV Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 28/37] KVM: X86: Introduce kvm_mmu_get_tdp_walk() for SEV-SNP use Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 29/37] KVM: X86: Define new RMP check related #NPF error bits Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 30/37] KVM: X86: update page-fault trace to log the 64-bit error code Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 31/37] KVM: SVM: Add support to handle GHCB GPA register VMGEXIT Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 32/37] KVM: SVM: Add support to handle MSR based Page State Change VMGEXIT Brijesh Singh
2021-05-10 17:30 ` Peter Gonda
2021-05-10 17:51 ` Brijesh Singh
2021-05-10 19:59 ` Peter Gonda
2021-05-10 20:50 ` Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 33/37] KVM: SVM: Add support to handle " Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 34/37] KVM: X86: Export the kvm_zap_gfn_range() for the SNP use Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 35/37] KVM: SVM: Add support to handle the RMP nested page fault Brijesh Singh
2021-04-30 12:38 ` [PATCH Part2 RFC v2 36/37] KVM: SVM: Provide support for SNP_GUEST_REQUEST NAE event Brijesh Singh
2021-05-10 18:57 ` Peter Gonda
2021-05-10 20:14 ` Brijesh Singh
2021-05-10 21:17 ` Sean Christopherson
2021-05-11 18:34 ` Brijesh Singh [this message]
2021-04-30 12:38 ` [PATCH Part2 RFC v2 37/37] KVM: SVM: Advertise the SEV-SNP feature support Brijesh Singh
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