From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f178.google.com (mail-pf1-f178.google.com [209.85.210.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EFEE829D6 for ; Mon, 19 Jul 2021 19:14:52 +0000 (UTC) Received: by mail-pf1-f178.google.com with SMTP id u126so9624214pfb.8 for ; Mon, 19 Jul 2021 12:14:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=tQHel7KfmZotRt+JL+tikCTH8i4jvKerKwX4Ykhe458=; b=XzM+UTgoPg+XkDOQ81Qyu9Aj1IHESyBIMhh/NFuqluTQUx/dfqwUh9CfJ7hyZrzFOq 98OBWEJ8SBib/jcg/gWXAgVqsGzmGzVmU1OUdWlfXwZp6TOhQz8JOPY/LhU0HLup5t60 MG09uBh/EZAN80GUdXbWAIzfSVF8OpL6KrxKsnW7KZT5qxtMjdXlgfFYJCVMyibNrxap bI8rESzefHOSN3QAHId4wLC6/nFzqtJ5ez4iL6x1w8/BsoenbhCPqleRFd2divXFsxNi r/lz770w0+7cZ8LA1ahJas+30qW/2CSV1uocE/OAPLcIqktisM8VvyTh0xw7f/nc4gbi Wsfg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=tQHel7KfmZotRt+JL+tikCTH8i4jvKerKwX4Ykhe458=; b=j9eSW2SZ4TPNf6oGYfB27skF3tkPe7ubP7QbzRZ0IJiARbmBMB//fm3WV6V4DHMbRJ lltw8DfMeeSJw7HL2/b4XI6eBlzxRniM8kIIVMu2dnPbVYgpIJ3o04PNy73hUug9TgJi NsuSa6V263Wm6XCeC5gCnpsfSSfaJ8nv+G8RI2i7euUm0ABRyQax3PC9eePP+06XpwsP 0gewCNEMsa4xMOr6R2ulDIXsL1CFZz3/WkWOD71avHHyFA/OaQdllpBVmnWQ3xWH0HpK WZTuVf3kM6the6dJJeMYEyrzHWeMJnavNSwjFduCd6wKk/R7l3Op1R1gTUvck3fTQsm0 Zovg== X-Gm-Message-State: AOAM530HDbv4YUn2XQAomm3/ozrj4By3QgPIPO3VEXtrgZVeZ0dqt0X/ hH4ywr6NvXfKN/tJgZQhfiqh1w== X-Google-Smtp-Source: ABdhPJwrFVVD96rnIFIK2jlY/ieHH+6lfcSv1ywrpxxBKG4B8nAAH7dSYEIACsmYQwT8smdf5ajGig== X-Received: by 2002:a65:5bc6:: with SMTP id o6mr3241244pgr.43.1626722092334; Mon, 19 Jul 2021 12:14:52 -0700 (PDT) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id x10sm22140073pgj.73.2021.07.19.12.14.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Jul 2021 12:14:51 -0700 (PDT) Date: Mon, 19 Jul 2021 19:14:48 +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 26/40] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_FINISH command Message-ID: References: <20210707183616.5620-1-brijesh.singh@amd.com> <20210707183616.5620-27-brijesh.singh@amd.com> <9ee5a991-3e43-3489-5ee1-ff8c66cfabc1@amd.com> <379fd4da-3ca9-3205-535b-8d1891b3a75a@amd.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <379fd4da-3ca9-3205-535b-8d1891b3a75a@amd.com> On Mon, Jul 19, 2021, Brijesh Singh wrote: > > > On 7/19/21 11:54 AM, Sean Christopherson wrote: > > > As I said in previous comments that by default all the memory is in the > > > hypervisor state. if the rmpupdate() failed that means nothing is changed in > > > the RMP and there is no need to reclaim. The reclaim is required only if the > > > pages are assigned in the RMP table. > > > > I wasn't referring to RMPUPDATE failing here (or anywhere). This is the vCPU free > > path, which I think means the svm->vmsa page was successfully updated in the RMP > > during LAUNCH_UPDATE. snp_launch_update_vmsa() goes through snp_page_reclaim() > > on LAUNCH_UPDATE failure, whereas this happy path does not. Is there some other > > transition during teardown that obviastes the need for reclaim? If so, a comment > > to explain that would be very helpful. > > > > In this patch, the sev_free_vcpu() hunk takes care of reclaiming the vmsa > pages before releasing it. I think it will make it more obvious after I add > a helper so that we don't depend on user reading the comment block to see > what its doing. Where? I feel like I'm missing something. The only change to sev_free_vcpu() I see is that addition of the rmpupdate(), I don't see any reclaim path. @@ -2346,8 +2454,25 @@ void sev_free_vcpu(struct kvm_vcpu *vcpu) if (vcpu->arch.guest_state_protected) sev_flush_guest_memory(svm, svm->vmsa, PAGE_SIZE); + + /* + * If its an SNP guest, then VMSA was added in the RMP entry as a guest owned page. + * Transition the page to hyperivosr state before releasing it back to the system. + */ + if (sev_snp_guest(vcpu->kvm)) { + struct rmpupdate e = {}; + int rc; + + rc = rmpupdate(virt_to_page(svm->vmsa), &e); + if (rc) { + pr_err("Failed to release SNP guest VMSA page (rc %d), leaking it\n", rc); + goto skip_vmsa_free; + } + } + __free_page(virt_to_page(svm->vmsa)); +skip_vmsa_free: if (svm->ghcb_sa_free) kfree(svm->ghcb_sa); }