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d="scan'208";a="10528545" From: Anthony PERARD To: Subject: [PATCH] Memory: Only call ramblock_ptr when needed in qemu_ram_writeback Date: Thu, 19 Dec 2019 15:43:22 +0000 Message-ID: <20191219154323.325255-1-anthony.perard@citrix.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20191219154214.GE1267@perard.uk.xensource.com> References: <20191219154214.GE1267@perard.uk.xensource.com> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: FreeBSD 9.x [fuzzy] X-Received-From: 216.71.155.144 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Beata Michalska , Juan Quintela , "Dr. David Alan Gilbert" , Anthony PERARD , Paolo Bonzini , Richard Henderson Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" It is possible that a ramblock doesn't have memory that QEMU can access, this is the case with the Xen hypervisor. In order to avoid to trigger an assert, only call ramblock_ptr() when needed in qemu_ram_writeback(). This should fix migration of Xen guests that was broken with bd108a44bc29 ("migration: ram: Switch to ram block writeback"). Signed-off-by: Anthony PERARD Reviewed-by: Juan Quintela Acked-by: Paolo Bonzini --- exec.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/exec.c b/exec.c index a34c34818404..b11010e0cb4c 100644 --- a/exec.c +++ b/exec.c @@ -2166,14 +2166,13 @@ int qemu_ram_resize(RAMBlock *block, ram_addr_t newsize, Error **errp) */ void qemu_ram_writeback(RAMBlock *block, ram_addr_t start, ram_addr_t length) { - void *addr = ramblock_ptr(block, start); - /* The requested range should fit in within the block range */ g_assert((start + length) <= block->used_length); #ifdef CONFIG_LIBPMEM /* The lack of support for pmem should not block the sync */ if (ramblock_is_pmem(block)) { + void *addr = ramblock_ptr(block, start); pmem_persist(addr, length); return; } @@ -2184,6 +2183,7 @@ void qemu_ram_writeback(RAMBlock *block, ram_addr_t start, ram_addr_t length) * specified as persistent (or is not one) - use the msync. * Less optimal but still achieves the same goal */ + void *addr = ramblock_ptr(block, start); if (qemu_msync(addr, length, block->fd)) { warn_report("%s: failed to sync memory range: start: " RAM_ADDR_FMT " length: " RAM_ADDR_FMT,