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From: Sean Christopherson <seanjc@google.com>
To: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Borislav Petkov <bp@suse.de>,
	Brijesh Singh <brijesh.singh@amd.com>
Subject: Re: [PATCH v2 02/14] KVM: SVM: Free sev_asid_bitmap during init if SEV setup fails
Date: Thu, 14 Jan 2021 11:17:27 -0800	[thread overview]
Message-ID: <YACYx68nBGOe2ROg@google.com> (raw)
In-Reply-To: <12cfd19a-7f6f-c422-5d6a-5317c1df72ae@amd.com>

On Thu, Jan 14, 2021, Tom Lendacky wrote:
> On 1/14/21 11:12 AM, Sean Christopherson wrote:
> > On Thu, Jan 14, 2021, Tom Lendacky wrote:
> > > On 1/13/21 6:36 PM, Sean Christopherson wrote:
> > > > Free sev_asid_bitmap if the reclaim bitmap allocation fails, othwerise
> > > > KVM will unnecessarily keep the bitmap when SEV is not fully enabled.
> > > > 
> > > > Freeing the page is also necessary to avoid introducing a bug when a
> > > > future patch eliminates svm_sev_enabled() in favor of using the global
> > > > 'sev' flag directly.  While sev_hardware_enabled() checks max_sev_asid,
> > > > which is true even if KVM setup fails, 'sev' will be true if and only
> > > > if KVM setup fully succeeds.
> > > > 
> > > > Fixes: 33af3a7ef9e6 ("KVM: SVM: Reduce WBINVD/DF_FLUSH invocations")
> 
> Oops, missed this last time... I don't think the Fixes: tag is needed
> anymore unless you don't want the memory consumption of the first bitmap,

If Fixes is viewed as purely a "this needs to be backported", then yes, it
should be dropped.  But, since KVM policy is to backport only patches that are
explicitly tagged with stable@, I like to use to Fixes to create a paper trail
for bug fixes even if the bug is essentially benign.

That being said, I have no objection to dropping it if anyone feels strongly
about not playing fast and loose with Fixes.

> should the allocation of the second bitmap fail, until kvm_amd is rmmod'ed.
> Up to you.

  reply	other threads:[~2021-01-14 19:18 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-14  0:36 [PATCH v2 00/14] KVM: SVM: Misc SEV cleanups Sean Christopherson
2021-01-14  0:36 ` [PATCH v2 01/14] KVM: SVM: Zero out the VMCB array used to track SEV ASID association Sean Christopherson
2021-01-14 15:56   ` Tom Lendacky
2021-01-14 17:13     ` Sean Christopherson
2021-01-14 20:57   ` Brijesh Singh
2021-01-14  0:36 ` [PATCH v2 02/14] KVM: SVM: Free sev_asid_bitmap during init if SEV setup fails Sean Christopherson
2021-01-14 15:49   ` Tom Lendacky
2021-01-14 17:12     ` Sean Christopherson
2021-01-14 18:02       ` Tom Lendacky
2021-01-14 19:17         ` Sean Christopherson [this message]
2021-01-14  0:36 ` [PATCH v2 03/14] KVM: SVM: Move SEV module params/variables to sev.c Sean Christopherson
2021-01-14 19:07   ` Tom Lendacky
2021-01-14 20:59   ` Brijesh Singh
2021-01-14  0:36 ` [PATCH v2 04/14] x86/cpufeatures: Assign dedicated feature word for AMD mem encryption Sean Christopherson
2021-01-14 11:35   ` Borislav Petkov
2021-01-14 17:09     ` Sean Christopherson
2021-01-14 17:16       ` Borislav Petkov
2021-01-28 15:09         ` Paolo Bonzini
2021-01-14 21:17   ` Brijesh Singh
2021-01-14  0:36 ` [PATCH v2 05/14] KVM: x86: Override reported SME/SEV feature flags with host mask Sean Christopherson
2021-01-14 21:18   ` Brijesh Singh
2021-01-28 15:07   ` Paolo Bonzini
2021-01-28 17:09     ` Sean Christopherson
2021-01-28 17:25       ` Paolo Bonzini
2021-01-14  0:37 ` [PATCH v2 06/14] x86/sev: Drop redundant and potentially misleading 'sev_enabled' Sean Christopherson
2021-01-14 17:54   ` Tom Lendacky
2021-01-14 21:24   ` Brijesh Singh
2021-01-14  0:37 ` [PATCH v2 07/14] KVM: SVM: Append "_enabled" to module-scoped SEV/SEV-ES control variables Sean Christopherson
2021-01-14 21:28   ` Brijesh Singh
2021-01-14  0:37 ` [PATCH v2 08/14] KVM: SVM: Condition sev_enabled and sev_es_enabled on CONFIG_KVM_AMD_SEV=y Sean Christopherson
2021-01-14 20:56   ` Tom Lendacky
2021-01-14 21:28   ` Brijesh Singh
2021-01-14  0:37 ` [PATCH v2 09/14] KVM: SVM: Unconditionally invoke sev_hardware_teardown() Sean Christopherson
2021-01-14 21:26   ` Tom Lendacky
2021-01-14 21:32   ` Brijesh Singh
2021-01-14  0:37 ` [PATCH v2 10/14] KVM: SVM: Explicitly check max SEV ASID during sev_hardware_setup() Sean Christopherson
2021-01-14 21:35   ` Brijesh Singh
2021-01-14 21:49   ` Tom Lendacky
2021-01-14  0:37 ` [PATCH v2 11/14] KVM: SVM: Move SEV VMCB tracking allocation to sev.c Sean Christopherson
2021-01-14 21:37   ` Brijesh Singh
2021-01-14 21:53     ` Tom Lendacky
2021-01-14 22:15   ` Tom Lendacky
2021-01-14  0:37 ` [PATCH v2 12/14] KVM: SVM: Drop redundant svm_sev_enabled() helper Sean Christopherson
2021-01-14 21:44   ` Brijesh Singh
2021-01-14 22:51   ` Tom Lendacky
2021-01-14  0:37 ` [PATCH v2 13/14] KVM: SVM: Remove an unnecessary prototype declaration of sev_flush_asids() Sean Christopherson
2021-01-14 21:45   ` Brijesh Singh
2021-01-14 22:53   ` Tom Lendacky
2021-01-14  0:37 ` [PATCH v2 14/14] KVM: SVM: Skip SEV cache flush if no ASIDs have been used Sean Christopherson
2021-01-15 15:07   ` Tom Lendacky
2021-01-15 17:19     ` Sean Christopherson
2021-01-28 15:10   ` Paolo Bonzini
2021-01-28 16:29     ` Sean Christopherson
2021-01-28 16:59       ` Paolo Bonzini

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