From 64fdad5e67587e88c2f1d8f294e89403856a4a31 Mon Sep 17 00:00:00 2001 From: Ira Weiny Date: Fri, 26 Jan 2024 12:01:24 +0000 Subject: [PATCH] cxl/cdat: Fix header sum value in CDAT checksum The addition of the DCD support for CXL type-3 devices extended the CDAT table large enough that the checksum being returned was incorrect.[1] This was because the checksum value was using the header length field rather than each of the 4 bytes of the length field. This was previously not seen because the length of the CDAT data was less than 256 thus resulting in an equivalent checksum value. Properly calculate the checksum for the CDAT header. [1] https://lore.kernel.org/all/20231116-fix-cdat-devm-free-v1-1-b148b40707d7@intel.com/ Fixes: aba578bdace5 ("hw/cxl/cdat: CXL CDAT Data Object Exchange implementation") Cc: Huai-Cheng Kuo Signed-off-by: Ira Weiny Reviewed-by: Dave Jiang Reviewed-by: Fan Ni Signed-off-by: Jonathan Cameron Message-Id: <20240126120132.24248-5-Jonathan.Cameron@huawei.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/cxl/cxl-cdat.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/hw/cxl/cxl-cdat.c b/hw/cxl/cxl-cdat.c index 24829cf242..2fea975671 100644 --- a/hw/cxl/cxl-cdat.c +++ b/hw/cxl/cxl-cdat.c @@ -49,6 +49,7 @@ static void ct3_build_cdat(CDATObject *cdat, Error **errp) g_autofree CDATTableHeader *cdat_header = NULL; g_autofree CDATEntry *cdat_st = NULL; uint8_t sum = 0; + uint8_t *hdr_buf; int ent, i; /* Use default table if fopen == NULL */ @@ -95,8 +96,12 @@ static void ct3_build_cdat(CDATObject *cdat, Error **errp) /* For now, no runtime updates */ cdat_header->sequence = 0; cdat_header->length += sizeof(CDATTableHeader); - sum += cdat_header->revision + cdat_header->sequence + - cdat_header->length; + + hdr_buf = (uint8_t *)cdat_header; + for (i = 0; i < sizeof(*cdat_header); i++) { + sum += hdr_buf[i]; + } + /* Sum of all bytes including checksum must be 0 */ cdat_header->checksum = ~sum + 1;