linux-kernel - Re: [PATCH v5 00/15] KVM: SVM: Misc SEV cleanups

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Date:   Thu, 22 Apr 2021 09:30:49 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Borislav Petkov <bp@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        Brijesh Singh <brijesh.singh@....com>
Subject: Re: [PATCH v5 00/15] KVM: SVM: Misc SEV cleanups

On 22/04/21 04:11, Sean Christopherson wrote:
> Minor bug fixes and refactorings of SEV related code, mainly to clean up
> the KVM code for tracking whether or not SEV and SEV-ES are enabled.  E.g.
> KVM has both sev_es and svm_sev_enabled(), and a global 'sev' flag while
> also using 'sev' as a local variable in several places.
> 
> Based kvm/queue-ish, commit 0e91d1992235 ("KVM: SVM: Allocate SEV command
> structures on local stack"), to avoid the conflicting CPUID.0x8000_001F
> patch sitting in kvm/queue.
> 
> v5:
>   - Use Paolo's version of the CPUID.0x8000_001F patch, with some of my
>     goo on top.  Paolo gets credit by introducing fewer bugs; v4 missed
>     the SEV/SEV-ES module params and used the wrong reverse-CPUID index...
>   - Add a patch to disable SEV/SEV-ES if NPT is disabled.
>   - Rebased, as above.
> v4:
>   - Reinstate the patch to override CPUID.0x8000_001F.
>   - Properly configure the CPUID.0x8000_001F override. [Paolo]
>   - Rebase to v5.12-rc1-dontuse.
> v3:
>   - Drop two patches: add a dedicated feature word for CPUID_0x8000001F,
>     and use the new word to mask host CPUID in KVM.  I'll send these as a
>     separate mini-series so that Boris can take them through tip.
>   - Add a patch to remove dependency on
>     CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT. [Boris / Paolo]
>   - Use kcalloc() instead of an open-coded equivalent. [Tom]
>   - Nullify sev_asid_bitmap when freeing it during setup. [Tom]
>   - Add a comment in sev_hardware_teardown() to document why it's safe to
>     query the ASID bitmap without taking the lock. [Tom]
>   - Collect reviews. [Tom and Brijesh]
> v2:
>   - Remove the kernel's sev_enabled instead of renaming it to sev_guest.
>   - Fix various build issues. [Tom]
>   - Remove stable tag from the patch to free sev_asid_bitmap.  Keeping the
>     bitmap on failure is truly only a leak once svm_sev_enabled() is
>     dropped later in the series.  It's still arguably a fix since KVM will
>     unnecessarily keep memory, but it's not stable material. [Tom]
>   - Collect one Ack. [Tom]
> 
> v1:
>   - https://lkml.kernel.org/r/20210109004714.1341275-1-seanjc@google.com
> 
> Paolo Bonzini (1):
>    KVM: SEV: Mask CPUID[0x8000001F].eax according to supported features
> 
> Sean Christopherson (14):
>    KVM: SVM: Zero out the VMCB array used to track SEV ASID association
>    KVM: SVM: Free sev_asid_bitmap during init if SEV setup fails
>    KVM: SVM: Disable SEV/SEV-ES if NPT is disabled
>    KVM: SVM: Move SEV module params/variables to sev.c
>    x86/sev: Drop redundant and potentially misleading 'sev_enabled'
>    KVM: SVM: Append "_enabled" to module-scoped SEV/SEV-ES control
>      variables
>    KVM: SVM: Condition sev_enabled and sev_es_enabled on
>      CONFIG_KVM_AMD_SEV=y
>    KVM: SVM: Enable SEV/SEV-ES functionality by default (when supported)
>    KVM: SVM: Unconditionally invoke sev_hardware_teardown()
>    KVM: SVM: Explicitly check max SEV ASID during sev_hardware_setup()
>    KVM: SVM: Move SEV VMCB tracking allocation to sev.c
>    KVM: SVM: Drop redundant svm_sev_enabled() helper
>    KVM: SVM: Remove an unnecessary prototype declaration of
>      sev_flush_asids()
>    KVM: SVM: Skip SEV cache flush if no ASIDs have been used
> 
>   arch/x86/include/asm/mem_encrypt.h |  1 -
>   arch/x86/kvm/cpuid.c               |  8 ++-
>   arch/x86/kvm/cpuid.h               |  1 +
>   arch/x86/kvm/svm/sev.c             | 80 ++++++++++++++++++++++--------
>   arch/x86/kvm/svm/svm.c             | 57 +++++++++------------
>   arch/x86/kvm/svm/svm.h             |  9 +---
>   arch/x86/mm/mem_encrypt.c          | 12 ++---
>   arch/x86/mm/mem_encrypt_identity.c |  1 -
>   8 files changed, 97 insertions(+), 72 deletions(-)
> 

Queued except for patch 6, send that separately since it's purely x86 
and maintainers will likely not notice it inside this thread.  You 
probably want to avoid conflicts by waiting for the migration patches, 
though.

Paolo