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Date: Thu, 23 Sep 2021 13:55:00 -0700 From: Marc Orr <marcorr@...gle.com> To: Brijesh Singh <brijesh.singh@....com> Cc: "Dr. David Alan Gilbert" <dgilbert@...hat.com>, x86 <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>, kvm list <kvm@...r.kernel.org>, linux-coco@...ts.linux.dev, linux-mm@...ck.org, linux-crypto@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>, Tom Lendacky <thomas.lendacky@....com>, "H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>, Paolo Bonzini <pbonzini@...hat.com>, Sean Christopherson <seanjc@...gle.com>, Vitaly Kuznetsov <vkuznets@...hat.com>, Wanpeng Li <wanpengli@...cent.com>, Jim Mattson <jmattson@...gle.com>, Andy Lutomirski <luto@...nel.org>, Dave Hansen <dave.hansen@...ux.intel.com>, Sergio Lopez <slp@...hat.com>, Peter Gonda <pgonda@...gle.com>, Peter Zijlstra <peterz@...radead.org>, Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>, David Rientjes <rientjes@...gle.com>, Dov Murik <dovmurik@...ux.ibm.com>, Tobin Feldman-Fitzthum <tobin@....com>, Borislav Petkov <bp@...en8.de>, Michael Roth <michael.roth@....com>, Vlastimil Babka <vbabka@...e.cz>, "Kirill A . Shutemov" <kirill@...temov.name>, Andi Kleen <ak@...ux.intel.com>, tony.luck@...el.com, sathyanarayanan.kuppuswamy@...ux.intel.com Subject: Re: [PATCH Part2 v5 21/45] KVM: SVM: Make AVIC backing, VMSA and VMCB memory allocation SNP safe On Thu, Sep 23, 2021 at 1:44 PM Brijesh Singh <brijesh.singh@....com> wrote: > > > On 9/23/21 2:17 PM, Marc Orr wrote: > > >>>> + > >>>> +struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu) > >>>> +{ > >>>> + unsigned long pfn; > >>>> + struct page *p; > >>>> + > >>>> + if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP)) > >>>> + return alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO); > > Continuing my other comment, above: if we introduce a > > `snp_globally_enabled` var, we could use that here, rather than > > `cpu_feature_enabled(X86_FEATURE_SEV_SNP)`. > > > Maybe I am missing something, what is wrong with > cpu_feature_enabled(...) check ? It's same as creating a global > variable. The feature enabled bit is not set if the said is not > enabled. See the patch #3 [1] in this series. > > [1] > https://lore.kernel.org/linux-mm/YUN+L0dlFMbC3bd4@zn.tnic/T/#m2ac1242b33abfcd0d9fb22a89f4c103eacf67ea7 > > thanks You are right. Patch #3 does exactly what I was asking for in `snp_rmptable_init()`. Thanks!
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