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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: AI3ShnDMH/tdhD4eI9G1FeD+e3J1fC694O/dxH49GREY3uGC74c30yZLUnXugxDlyWg8zI6xfnYJ7OJUhkmDSNbXaerUfTGADqlI43VkB/86opI/pNtLNOgsj7ZzdYuFAre8WVDCzVgQTAZMqSlUVHlKxcCa5a9veLOh2ITH6zY+vp4QEeRmA1TKalEcX44ZDIrTdPBwH+32cjkby6ZgolkXD9/Z/coCwV80XpOe0Al2AfZ+kAolLdIS4D3nK2GvHGwsPVQIQ0RzO25MJg2/BWTWJVKxpW1fYPBFz9AB+DIQE6PdQgjYtweRuIhc/FtLOujY7HheR4v3RSXINDoWietTaNBfrtUN+aO+L1ajuZR3bf2YBWfMSx8rsUay9vp+30FEz/90GfLocKcJacaLZeN1RiiLisSutgQ45kDomgmlqpPtNc6Uf3LF09KTclUp X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Mar 2026 17:46:28.3706 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: cd68e9f8-ad21-4f00-30cb-08de7e03cab9 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=[satlexmb08.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SA2PEPF00003F61.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR12MB5657 Hey Sean, On 07-03-2026 07:28, Sean Christopherson wrote: > On Thu, Jan 29, 2026, Shivansh Dhiman wrote: >> From: Neeraj Upadhyay >> >> The upcoming AMD FRED (Flexible Return and Event Delivery) feature >> introduces several new fields to the VMCB save area. These fields include >> FRED-specific stack pointers (fred_rsp[0-3], fred_ssp[1-3]), stack level >> tracking (fred_stklvls), and configuration (fred_config). >> >> Ensure that a vCPU starts with a clean and valid FRED state on >> capable hardware. Also update the size of save areas of VMCB. > >> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c >> index f4ccb3e66635..5cec971a1f5a 100644 >> --- a/arch/x86/kvm/svm/svm.c >> +++ b/arch/x86/kvm/svm/svm.c >> @@ -1110,6 +1110,16 @@ static void init_vmcb(struct kvm_vcpu *vcpu, bool init_event) >> save->idtr.base = 0; >> save->idtr.limit = 0xffff; >> >> + save->fred_rsp0 = 0; >> + save->fred_rsp1 = 0; >> + save->fred_rsp2 = 0; >> + save->fred_rsp3 = 0; >> + save->fred_stklvls = 0; >> + save->fred_ssp1 = 0; >> + save->fred_ssp2 = 0; >> + save->fred_ssp3 = 0; >> + save->fred_config = 0; > > Is this architecturally correct? I.e. are all the FRED MSRs zeroed on INIT? Yes that's right, the FRED MSRs are zeroed on init. - Shivansh