From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:49656) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gRESP-0004Bd-Ci for qemu-devel@nongnu.org; Mon, 26 Nov 2018 05:49:38 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gRESJ-0006m3-Dz for qemu-devel@nongnu.org; Mon, 26 Nov 2018 05:49:37 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37416) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gRESH-0006hH-L0 for qemu-devel@nongnu.org; Mon, 26 Nov 2018 05:49:31 -0500 From: Igor Mammedov Date: Mon, 26 Nov 2018 11:41:58 +0100 Message-Id: <1543228918-71172-1-git-send-email-imammedo@redhat.com> In-Reply-To: <20181123110106-mutt-send-email-mst@kernel.org> References: <20181123110106-mutt-send-email-mst@kernel.org> Subject: [Qemu-devel] [PATCH v2 1/2] pc: acpi: use correct RSDT length for checksum List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: sameo@linux.intel.com, mst@redhat.com AcpiRsdpDescriptor describes revision 2 RSDP table so using sizeof(*rsdp) for checksum calculation isn't correct since we are adding extra 16 bytes. But acpi_data_push() zeroes out table, so just by luck we are summing up exta zeros which still yelds correct checksum. Fix it up by explicitly stating table size instead of using pointer arithmetics on stucture. PS: Extra 16 bytes are still wasted, but droping them will break migration for machines older than 2.3 due to size mismatch, for 2.3 and older it's not an issue since they are using resizable memory regions (a1666142d) for ACPI blobs. So keep wasting memory to avoid breaking old machines. Fixes: 72c194f7e (i386: ACPI table generation code from seabios) Signed-off-by: Igor Mammedov --- there is no changes to the current RSDP content caused by this patch v2: - add 16 byte leak comment to the code (Michael) --- hw/i386/acpi-build.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c index 236a20e..5bb3563 100644 --- a/hw/i386/acpi-build.c +++ b/hw/i386/acpi-build.c @@ -2550,6 +2550,11 @@ build_amd_iommu(GArray *table_data, BIOSLinker *linker) static GArray * build_rsdp(GArray *rsdp_table, BIOSLinker *linker, unsigned rsdt_tbl_offset) { + /* AcpiRsdpDescriptor describes revision 2 RSDP table and as result we + * allocate extra 16 bytes for pc/q35 RSDP rev1 as well. Keep extra 16 bytes + * wasted to make sure we won't breake migration for machine types older + * than 2.3 due to size mismatch. + */ AcpiRsdpDescriptor *rsdp = acpi_data_push(rsdp_table, sizeof *rsdp); unsigned rsdt_pa_size = sizeof(rsdp->rsdt_physical_address); unsigned rsdt_pa_offset = @@ -2567,7 +2572,7 @@ build_rsdp(GArray *rsdp_table, BIOSLinker *linker, unsigned rsdt_tbl_offset) /* Checksum to be filled by Guest linker */ bios_linker_loader_add_checksum(linker, ACPI_BUILD_RSDP_FILE, - (char *)rsdp - rsdp_table->data, sizeof *rsdp, + (char *)rsdp - rsdp_table->data, 20 /* ACPI rev 1.0 RSDP size */, (char *)&rsdp->checksum - rsdp_table->data); return rsdp_table; -- 2.7.4