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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Nov 2025 04:57:10.5717 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 7cdc7171-47c1-4b00-3783-08de233a4507 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=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SN1PEPF0002636D.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN0PR12MB6366 Hi Yosry, On 13-11-2025 20:29, Yosry Ahmed wrote: > On Thu, Nov 13, 2025 at 05:28:11PM +0530, Shivansh Dhiman wrote: >> Hi Yosry, >> >> I tested this on EPYC-Turin and found that some tests seem to be a bit flaky. >> See below. > > Which ones? I was also running the tests on EPYC-Turin. Most of the nested LBRV tests had this issue. I checked your other patch to fix this. I tested it and it does fixes it for me. Thanks. >> >> On 11-11-2025 04:56, Yosry Ahmed wrote: >>> @@ -3058,55 +3041,64 @@ u64 dbgctl; >>> >>> static void svm_lbrv_test_guest1(void) >>> { >>> + u64 from_ip, to_ip; >>> + >>> /* >>> * This guest expects the LBR to be already enabled when it starts, >>> * it does a branch, and then disables the LBR and then checks. >>> */ >>> + dbgctl = rdmsr(MSR_IA32_DEBUGCTLMSR); >>> + TEST_EXPECT_EQ(dbgctl, DEBUGCTLMSR_LBR); >> >> This TEST_EXPECT_EQ is run when LBR is enabled, causing it to change last >> branch. I tried to move it below wrmsr(MSR_IA32_DEBUGCTLMSR, 0) and it works >> fine that way. > > It shouldn't matter though because we execute the branch we care about > after TEST_EXPECT_EQ(), it's DO_BRANCH(guest_branch0) below. Is it > possible that the compiler reordered them for some reason? > > I liked having the check here because it's easier to follow when the > checks are done at their logical place rather than delayed after > wrmsr(). Correct, that should be the natural order. >> >>> >>> DO_BRANCH(guest_branch0); >>> >>> - dbgctl = rdmsr(MSR_IA32_DEBUGCTLMSR); >>> + /* Disable LBR before the checks to avoid changing the last branch */ >>> wrmsr(MSR_IA32_DEBUGCTLMSR, 0);> + dbgctl = rdmsr(MSR_IA32_DEBUGCTLMSR); >>> + TEST_EXPECT_EQ(dbgctl, 0); >>> >>> - if (dbgctl != DEBUGCTLMSR_LBR) >>> - asm volatile("ud2\n"); >>> - if (rdmsr(MSR_IA32_DEBUGCTLMSR) != 0) >>> - asm volatile("ud2\n"); >>> + get_lbr_ips(&from_ip, &to_ip); >>> + TEST_EXPECT_EQ((u64)&guest_branch0_from, from_ip); >>> + TEST_EXPECT_EQ((u64)&guest_branch0_to, to_ip); >>> >>> - GUEST_CHECK_LBR(&guest_branch0_from, &guest_branch0_to); >>> asm volatile ("vmmcall\n"); >>> } >>> >>> static void svm_lbrv_test_guest2(void) >>> { >>> + u64 from_ip, to_ip; >>> + >>> /* >>> * This guest expects the LBR to be disabled when it starts, >>> * enables it, does a branch, disables it and then checks. >>> */ >>> - >>> - DO_BRANCH(guest_branch1); >>> dbgctl = rdmsr(MSR_IA32_DEBUGCTLMSR); >>> + TEST_EXPECT_EQ(dbgctl, 0); >>> >>> - if (dbgctl != 0) >>> - asm volatile("ud2\n"); >>> + DO_BRANCH(guest_branch1); >>> >>> - GUEST_CHECK_LBR(&host_branch2_from, &host_branch2_to); >>> + get_lbr_ips(&from_ip, &to_ip); >>> + TEST_EXPECT_EQ((u64)&host_branch2_from, from_ip); >>> + TEST_EXPECT_EQ((u64)&host_branch2_to, to_ip); >>> >>> wrmsr(MSR_IA32_DEBUGCTLMSR, DEBUGCTLMSR_LBR); >>> dbgctl = rdmsr(MSR_IA32_DEBUGCTLMSR); >>> + TEST_EXPECT_EQ(dbgctl, DEBUGCTLMSR_LBR); >> >> Same thing here as well. >> >>> + >>> DO_BRANCH(guest_branch2); >>> wrmsr(MSR_IA32_DEBUGCTLMSR, 0); >>> >>> - if (dbgctl != DEBUGCTLMSR_LBR) >>> - asm volatile("ud2\n"); >>> - GUEST_CHECK_LBR(&guest_branch2_from, &guest_branch2_to); >>> + get_lbr_ips(&from_ip, &to_ip); >>> + TEST_EXPECT_EQ((u64)&guest_branch2_from, from_ip); >>> + TEST_EXPECT_EQ((u64)&guest_branch2_to, to_ip); >>> >>> asm volatile ("vmmcall\n"); >>> } >> Reviewed-by: Shivansh Dhiman >> >> Other tests look good to me, and work fine. >> >> Tested-by: Shivansh Dhiman > > Thanks!