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[35.185.214.157]) by smtp.gmail.com with ESMTPSA id u24sm22109816pfm.141.2021.07.19.12.14.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Jul 2021 12:14:18 -0700 (PDT) Date: Mon, 19 Jul 2021 19:14:15 +0000 From: Sean Christopherson To: Brijesh Singh 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 , Ingo Molnar , Joerg Roedel , Tom Lendacky , "H. Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Andy Lutomirski , Dave Hansen , Sergio Lopez , Peter Gonda , Peter Zijlstra , Srinivas Pandruvada , David Rientjes , Dov Murik , Tobin Feldman-Fitzthum , Borislav Petkov , Michael Roth , Vlastimil Babka , tony.luck@intel.com, npmccallum@redhat.com, brijesh.ksingh@gmail.com Subject: Re: [PATCH Part2 RFC v4 25/40] KVM: SVM: Reclaim the guest pages when SEV-SNP VM terminates Message-ID: References: <20210707183616.5620-1-brijesh.singh@amd.com> <20210707183616.5620-26-brijesh.singh@amd.com> <2711d9f9-21a0-7baa-d0ff-2c0f69ca6949@amd.com> <912c929c-06ba-a391-36bb-050384907d81@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 19, 2021, Sean Christopherson wrote: > On Mon, Jul 19, 2021, Brijesh Singh wrote: > > > > On 7/19/21 12:18 PM, Sean Christopherson wrote: > > > > > > > > Okay, I will add helper to make things easier. One case where we will > > > > need to directly call the rmpupdate() is during the LAUNCH_UPDATE > > > > command. In that case the page is private and its immutable bit is also > > > > set. This is because the firmware makes change to the page, and we are > > > > required to set the immutable bit before the call. > > > > > > Or do "int rmp_make_firmware(u64 pfn, bool immutable)"? > > > > That's not what we need. > > > > We need 'rmp_make_private() + immutable' all in one RMPUPDATE. Here is the > > snippet from SNP_LAUNCH_UPDATE. > > Ah, not firmwrare, gotcha. But we can still use a helper, e.g. an inner > double-underscore helper, __rmp_make_private(). Hmm, looking at it again, I think I also got confused by the comment for the VMSA page: /* Transition the VMSA page to a firmware state. */ e.assigned = 1; e.immutable = 1; e.asid = sev->asid; e.gpa = -1; e.pagesize = RMP_PG_SIZE_4K; Unlike __snp_alloc_firmware_pages() in the CCP code, the VMSA is associated with the guest's ASID, just not a GPA. I.e. the VMSA is more of a specialized guest private page, as opposed to a dedicated firmware page. I.e. a __rmp_make_private() and/or rmp_make_private_immutable() definitely seems like a good idea.