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Date:   Fri, 15 Oct 2021 20:27:29 +0000
From:   Sean Christopherson <seanjc@google.com>
To:     Brijesh Singh <brijesh.singh@amd.com>
Cc:     x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        linux-coco@lists.linux.dev, linux-mm@kvack.org,
        linux-crypto@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Joerg Roedel <jroedel@suse.de>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Ard Biesheuvel <ardb@kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Sergio Lopez <slp@redhat.com>, Peter Gonda <pgonda@google.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        David Rientjes <rientjes@google.com>,
        Dov Murik <dovmurik@linux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@ibm.com>,
        Borislav Petkov <bp@alien8.de>,
        Michael Roth <michael.roth@amd.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        "Kirill A . Shutemov" <kirill@shutemov.name>,
        Andi Kleen <ak@linux.intel.com>, tony.luck@intel.com,
        marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com
Subject: Re: [PATCH Part2 v5 05/45] x86/sev: Add helper functions for
 RMPUPDATE and PSMASH instruction
Message-ID: <YWnkMXdL89AHPF10@google.com>
References: <20210820155918.7518-1-brijesh.singh@amd.com>
 <20210820155918.7518-6-brijesh.singh@amd.com>
 <YWnC++azH3xXrMm6@google.com>
 <3fc1b403-73a1-cf2e-2990-66d2c1ecdfa3@amd.com>
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On Fri, Oct 15, 2021, Brijesh Singh wrote:
> On 10/15/21 1:05 PM, Sean Christopherson wrote:
> > On Fri, Aug 20, 2021, Brijesh Singh wrote:
> >> +	if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP))
> > Shouldn't this be a WARN_ON_ONCE()?
> 
> Since some of these function are called while handling the PSC so I
> tried to avoid using the WARN -- mainly because if the warn_on_panic=1
> is set on the host then it will result in the kernel panic.

But why would KVM be handling PSC requests if SNP is disabled?