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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Nov 2022 23:39:22.2609 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: dad9e2f2-0aad-4603-29c6-08dac2aba106 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BN8NAM11FT023.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5301 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 09, 2022 at 03:53:36PM -0500, Tianyu Lan wrote: > From: Tianyu Lan > > Hypervisor may pass cc blob address directly into boot param's cc > blob address in the direct boot mode. Check cc blcb hdr magic first > in the sev_enable() and use it as cc blob address if check successfully. > > Signed-off-by: Tianyu Lan > --- > arch/x86/boot/compressed/sev.c | 27 ++++++++++++++++++++------- > 1 file changed, 20 insertions(+), 7 deletions(-) > > diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c > index c93930d5ccbd..960968f8bf75 100644 > --- a/arch/x86/boot/compressed/sev.c > +++ b/arch/x86/boot/compressed/sev.c > @@ -272,17 +272,24 @@ static void enforce_vmpl0(void) > > void sev_enable(struct boot_params *bp) > { > + struct cc_blob_sev_info *cc_info; > unsigned int eax, ebx, ecx, edx; > struct msr m; > bool snp; > > /* > - * bp->cc_blob_address should only be set by boot/compressed kernel. > - * Initialize it to 0 to ensure that uninitialized values from > - * buggy bootloaders aren't propagated. > + * bp->cc_blob_address should only be set by boot/compressed > + * kernel and hypervisor with direct boot mode. Initialize it > + * to 0 after checking in order to ensure that uninitialized > + * values from buggy bootloaders aren't propagated. > */ > - if (bp) > - bp->cc_blob_address = 0; > + if (bp) { > + cc_info = (struct cc_blob_sev_info *)(unsigned long) > + bp->cc_blob_address; > + > + if (cc_info->magic != CC_BLOB_SEV_HDR_MAGIC) > + bp->cc_blob_address = 0; It doesn't seem great to rely on SEV_HDR_MAGIC to determine whether bp->cc_blob_address is valid or not since it is only a 32-bit value. Would it be possible to use a setup_data entry of type SETUP_CC_BLOB in bp->hdr.setup_data instead? There's already handling for that in find_cc_blob_setup_data() so it should "just work". -Mike