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([2404:f801:9000:18:efec::75b]) by smtp.gmail.com with ESMTPSA id x2-20020a17090aa38200b0023b3d80c76csm2098025pjp.4.2023.04.13.21.40.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 13 Apr 2023 21:40:55 -0700 (PDT) Message-ID: <583dd8ba-24f8-c1c6-256b-21a00ae3bd0a@gmail.com> Date: Fri, 14 Apr 2023 12:40:44 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [RFC PATCH V4 06/17] x86/hyperv: decrypt VMBus pages for sev-snp enlightened guest To: "Michael Kelley (LINUX)" , "luto@kernel.org" , "tglx@linutronix.de" , "mingo@redhat.com" , "bp@alien8.de" , "dave.hansen@linux.intel.com" , "x86@kernel.org" , "hpa@zytor.com" , "seanjc@google.com" , "pbonzini@redhat.com" , "jgross@suse.com" , Tianyu Lan , "kirill@shutemov.name" , "jiangshan.ljs@antgroup.com" , "peterz@infradead.org" , "ashish.kalra@amd.com" , "srutherford@google.com" , "akpm@linux-foundation.org" , "anshuman.khandual@arm.com" , "pawan.kumar.gupta@linux.intel.com" , "adrian.hunter@intel.com" , "daniel.sneddon@linux.intel.com" , "alexander.shishkin@linux.intel.com" , "sandipan.das@amd.com" , "ray.huang@amd.com" , "brijesh.singh@amd.com" , "michael.roth@amd.com" , "thomas.lendacky@amd.com" , "sterritt@google.com" , "tony.luck@intel.com" , "samitolvanen@google.com" , "fenghua.yu@intel.com" Cc: "pangupta@amd.com" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , "linux-hyperv@vger.kernel.org" , "linux-arch@vger.kernel.org" References: <20230403174406.4180472-1-ltykernel@gmail.com> <20230403174406.4180472-7-ltykernel@gmail.com> From: Tianyu Lan In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On 4/12/2023 10:32 PM, Michael Kelley (LINUX) wrote: >> @@ -191,6 +222,15 @@ void hv_synic_free(void) >> free_page((unsigned long)hv_cpu->synic_event_page); >> free_page((unsigned long)hv_cpu->synic_message_page); >> free_page((unsigned long)hv_cpu->post_msg_page); >> + >> + if (hv_isolation_type_en_snp()) { >> + set_memory_encrypted((unsigned long) >> + hv_cpu->synic_message_page, 1); >> + set_memory_encrypted((unsigned long) >> + hv_cpu->synic_event_page, 1); >> + set_memory_encrypted((unsigned long) >> + hv_cpu->post_msg_page, 1); >> + } > The re-encryption must be done*before* pages are freed! > > Furthermore, if the re-encryption fails, we should not free > the page as it would pollute the free memory pool. The best > we can do is leak the memory. See Patch 5 in Dexuan's > TDX series, which does the same thing (but still doesn't > get it quite right, per my comments). > You are right. The order is wrong. we should figure out a right solution to handle such case.