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Mon, 27 Jan 2025 21:31:27 +0000 Received: from CH3PR10MB7329.namprd10.prod.outlook.com ([fe80::f238:6143:104c:da23]) by CH3PR10MB7329.namprd10.prod.outlook.com ([fe80::f238:6143:104c:da23%6]) with mapi id 15.20.8377.021; Mon, 27 Jan 2025 21:31:26 +0000 From: =?utf-8?q?=E2=80=9CWilliam_Roche?= To: david@redhat.com, kvm@vger.kernel.org, qemu-devel@nongnu.org, qemu-arm@nongnu.org Cc: william.roche@oracle.com, peterx@redhat.com, pbonzini@redhat.com, richard.henderson@linaro.org, philmd@linaro.org, peter.maydell@linaro.org, mtosatti@redhat.com, imammedo@redhat.com, eduardo@habkost.net, marcel.apfelbaum@gmail.com, wangyanan55@huawei.com, zhao1.liu@intel.com, joao.m.martins@oracle.com Subject: [PATCH v6 2/6] system/physmem: poisoned memory discard on reboot Date: Mon, 27 Jan 2025 21:31:03 +0000 Message-ID: <20250127213107.3454680-3-william.roche@oracle.com> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20250127213107.3454680-1-william.roche@oracle.com> References: <20250127213107.3454680-1-william.roche@oracle.com> X-ClientProxiedBy: LO4P123CA0285.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:195::20) To CH3PR10MB7329.namprd10.prod.outlook.com (2603:10b6:610:12c::16) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH3PR10MB7329:EE_|PH0PR10MB4614:EE_ X-MS-Office365-Filtering-Correlation-Id: c080f76c-0a11-4ddb-8551-08dd3f19f49b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|7416014|376014; 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If the kernel doesn't support the madvise calls used by this function and we are dealing with anonymous memory, fall back to remapping the location(s). Signed-off-by: William Roche Acked-by: David Hildenbrand --- system/physmem.c | 54 ++++++++++++++++++++++++++++-------------------- 1 file changed, 32 insertions(+), 22 deletions(-) diff --git a/system/physmem.c b/system/physmem.c index 3dd2adde73..3dc10ae27b 100644 --- a/system/physmem.c +++ b/system/physmem.c @@ -2167,6 +2167,23 @@ void qemu_ram_free(RAMBlock *block) } #ifndef _WIN32 +/* Simply remap the given VM memory location from start to start+length */ +static int qemu_ram_remap_mmap(RAMBlock *block, uint64_t start, size_t length) +{ + int flags, prot; + void *area; + void *host_startaddr = block->host + start; + + assert(block->fd < 0); + flags = MAP_FIXED | MAP_ANONYMOUS; + flags |= block->flags & RAM_SHARED ? MAP_SHARED : MAP_PRIVATE; + flags |= block->flags & RAM_NORESERVE ? MAP_NORESERVE : 0; + prot = PROT_READ; + prot |= block->flags & RAM_READONLY ? 0 : PROT_WRITE; + area = mmap(host_startaddr, length, prot, flags, -1, 0); + return area != host_startaddr ? -errno : 0; +} + /* * qemu_ram_remap - remap a single RAM page * @@ -2184,9 +2201,7 @@ void qemu_ram_remap(ram_addr_t addr) { RAMBlock *block; uint64_t offset; - int flags; - void *area, *vaddr; - int prot; + void *vaddr; size_t page_size; RAMBLOCK_FOREACH(block) { @@ -2201,25 +2216,20 @@ void qemu_ram_remap(ram_addr_t addr) ; } else if (xen_enabled()) { abort(); - } else { - flags = MAP_FIXED; - flags |= block->flags & RAM_SHARED ? - MAP_SHARED : MAP_PRIVATE; - flags |= block->flags & RAM_NORESERVE ? MAP_NORESERVE : 0; - prot = PROT_READ; - prot |= block->flags & RAM_READONLY ? 0 : PROT_WRITE; - if (block->fd >= 0) { - area = mmap(vaddr, page_size, prot, flags, block->fd, - offset + block->fd_offset); - } else { - flags |= MAP_ANONYMOUS; - area = mmap(vaddr, page_size, prot, flags, -1, 0); - } - if (area != vaddr) { - error_report("Could not remap RAM %s:%" PRIx64 "+%" PRIx64 - " +%zx", block->idstr, offset, - block->fd_offset, page_size); - exit(1); + if (ram_block_discard_range(block, offset, page_size) != 0) { + /* + * Fall back to using mmap() only for anonymous mapping, + * as if a backing file is associated we may not be able + * to recover the memory in all cases. + * So don't take the risk of using only mmap and fail now. + */ + if (block->fd >= 0 || + qemu_ram_remap_mmap(block, offset, page_size) != 0) { + error_report("Could not remap RAM %s:%" PRIx64 "+%" + PRIx64 " +%zx", block->idstr, offset, + block->fd_offset, page_size); + exit(1); + } } memory_try_enable_merging(vaddr, page_size); qemu_ram_setup_dump(vaddr, page_size);