Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Thu, 15 Jul 2021 18:39:12 +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-efi@vger.kernel.org, platform-driver-x86@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>, tony.luck@intel.com,
        npmccallum@redhat.com, brijesh.ksingh@gmail.com
Subject: Re: [PATCH Part2 RFC v4 07/40] x86/sev: Split the physmap when
 adding the page in RMP table
Message-ID: <YPCA0A+Z3RKfdsa3@google.com>
References: <20210707183616.5620-1-brijesh.singh@amd.com>
 <20210707183616.5620-8-brijesh.singh@amd.com>
 <YO9kP1v0TAFXISHD@google.com>
 <d486a008-8340-66b0-9667-11c8a50974e4@amd.com>
 <YPB1n0+G+0EoyEvE@google.com>
 <41f83ddf-a8a5-daf3-dc77-15fc164f77c6@amd.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <41f83ddf-a8a5-daf3-dc77-15fc164f77c6@amd.com>
Precedence: bulk

On Thu, Jul 15, 2021, Brijesh Singh wrote:
> The memfd_secrets uses the set_direct_map_{invalid,default}_noflush() and it
> is designed to remove/add the present bit in the direct map. We can't use
> them, because in our case the page may get accessed by the KVM (e.g
> kvm_guest_write, kvm_guest_map etc).

But KVM should never access a guest private page, i.e. the direct map should
always be restored to PRESENT before KVM attempts to access the page.