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Mon, 1 Nov 2021 10:21:53 GMT Received: from b03ledav003.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2C1B66A051; Mon, 1 Nov 2021 10:21:53 +0000 (GMT) Received: from b03ledav003.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7849C6A05D; Mon, 1 Nov 2021 10:21:52 +0000 (GMT) Received: from amdrome3.watson.ibm.com (unknown [9.2.130.16]) by b03ledav003.gho.boulder.ibm.com (Postfix) with ESMTP; Mon, 1 Nov 2021 10:21:52 +0000 (GMT) From: Dov Murik To: qemu-devel@nongnu.org Subject: [PATCH 3/3] sev/i386: Perform padding calculations at compile-time Date: Mon, 1 Nov 2021 10:21:36 +0000 Message-Id: <20211101102136.1706421-4-dovmurik@linux.ibm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20211101102136.1706421-1-dovmurik@linux.ibm.com> References: <20211101102136.1706421-1-dovmurik@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: JXz2PqvFzQ43ueYIItHgdW1nsQMRtGMm X-Proofpoint-ORIG-GUID: oe-LEZqZnY7HmtbXgw8zpkgUycLeoiA4 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.182.1,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.0.607.475 definitions=2021-11-01_04,2021-11-01_01,2020-04-07_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 phishscore=0 adultscore=0 clxscore=1015 spamscore=0 bulkscore=0 lowpriorityscore=0 suspectscore=0 impostorscore=0 mlxlogscore=999 malwarescore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2111010058 Received-SPF: pass client-ip=148.163.156.1; envelope-from=dovmurik@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -19 X-Spam_score: -2.0 X-Spam_bar: -- X-Spam_report: (-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Tom Lendacky , Ashish Kalra , Brijesh Singh , Eduardo Habkost , James Bottomley , Marcelo Tosatti , "Dr. David Alan Gilbert" , Dov Murik , Tobin Feldman-Fitzthum , Paolo Bonzini , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" In sev_add_kernel_loader_hashes, the sizes of structs are known at compile-time, so calculate needed padding at compile-time. No functional change intended. Signed-off-by: Dov Murik Reviewed-by: Dr. David Alan Gilbert Reviewed-by: Philippe Mathieu-Daudé --- target/i386/sev.c | 28 ++++++++++++++++++---------- 1 file changed, 18 insertions(+), 10 deletions(-) diff --git a/target/i386/sev.c b/target/i386/sev.c index a20ddb545e..c09de9c6f0 100644 --- a/target/i386/sev.c +++ b/target/i386/sev.c @@ -109,9 +109,19 @@ typedef struct QEMU_PACKED SevHashTable { SevHashTableEntry cmdline; SevHashTableEntry initrd; SevHashTableEntry kernel; - uint8_t padding[]; } SevHashTable; +/* + * Data encrypted by sev_encrypt_flash() must be padded to a multiple of + * 16 bytes. + */ +typedef struct QEMU_PACKED PaddedSevHashTable { + SevHashTable ht; + uint8_t padding[ROUND_UP(sizeof(SevHashTable), 16) - sizeof(SevHashTable)]; +} PaddedSevHashTable; + +QEMU_BUILD_BUG_ON(sizeof(PaddedSevHashTable) % 16 != 0); + static SevGuestState *sev_guest; static Error *sev_mig_blocker; @@ -1196,19 +1206,19 @@ bool sev_add_kernel_loader_hashes(SevKernelLoaderContext *ctx, Error **errp) uint8_t *data; SevHashTableDescriptor *area; SevHashTable *ht; + PaddedSevHashTable *padded_ht; uint8_t cmdline_hash[HASH_SIZE]; uint8_t initrd_hash[HASH_SIZE]; uint8_t kernel_hash[HASH_SIZE]; uint8_t *hashp; size_t hash_len = HASH_SIZE; - int aligned_len = ROUND_UP(sizeof(SevHashTable), 16); if (!pc_system_ovmf_table_find(SEV_HASH_TABLE_RV_GUID, &data, NULL)) { warn_report("SEV: kernel specified but OVMF has no hash table guid"); return false; } area = (SevHashTableDescriptor *)data; - if (!area->base || area->size < aligned_len) { + if (!area->base || area->size < sizeof(PaddedSevHashTable)) { warn_report("SEV: OVMF's hashes table area is invalid (base=0x%x size=0x%x)", area->base, area->size); return false; @@ -1253,7 +1263,8 @@ bool sev_add_kernel_loader_hashes(SevKernelLoaderContext *ctx, Error **errp) * Populate the hashes table in the guest's memory at the OVMF-designated * area for the SEV hashes table */ - ht = qemu_map_ram_ptr(NULL, area->base); + padded_ht = qemu_map_ram_ptr(NULL, area->base); + ht = &padded_ht->ht; ht->guid = sev_hash_table_header_guid; ht->len = sizeof(*ht); @@ -1270,13 +1281,10 @@ bool sev_add_kernel_loader_hashes(SevKernelLoaderContext *ctx, Error **errp) ht->kernel.len = sizeof(ht->kernel); memcpy(ht->kernel.hash, kernel_hash, sizeof(ht->kernel.hash)); - /* When calling sev_encrypt_flash, the length has to be 16 byte aligned */ - if (aligned_len != ht->len) { - /* zero the excess data so the measurement can be reliably calculated */ - memset(ht->padding, 0, aligned_len - ht->len); - } + /* zero the excess data so the measurement can be reliably calculated */ + memset(padded_ht->padding, 0, sizeof(padded_ht->padding)); - if (sev_encrypt_flash((uint8_t *)ht, aligned_len, errp) < 0) { + if (sev_encrypt_flash((uint8_t *)padded_ht, sizeof(*padded_ht), errp) < 0) { return false; }