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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Sep 2023 14:06:25.9752 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 370f1951-f801-4dd1-4ca7-08dbb52bc8dc 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: CO1PEPF000044F3.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR12MB7103 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Zen 4 systems running buggy microcode can hit a WARN_ON() in the PMI handler, as shown below, several times while perf runs. A simple `perf top` run is enough to render the system unusable. WARNING: CPU: 18 PID: 20608 at arch/x86/events/amd/core.c:944 amd_pmu_v2_ha= ndle_irq+0x1be/0x2b0 This happens because the Performance Counter Global Status Register (PerfCntGlobalStatus) has one or more bits set which are considered reserved according to the "AMD64 Architecture Programmer\ufffd\ufffd\ufffds= Manual, Volume 2: System Programming, 24593". The document can be found at https://www.amd.com/system/files/TechDocs/24593.pdf To make this less intrusive, warn just once if any reserved bit is set and prompt the user to update the microcode. Also sanitize the value to what the code is handling, so that the overflow events continue to be handled for the number of counters that are known to be sane. Going forward, the following microcode patch levels are recommended for Zen 4 processors in order to avoid such issues with reserved bits. Family=3D0x19 Model=3D0x11 Stepping=3D0x01: Patch=3D0x0a10113e Family=3D0x19 Model=3D0x11 Stepping=3D0x02: Patch=3D0x0a10123e Family=3D0x19 Model=3D0xa0 Stepping=3D0x01: Patch=3D0x0aa00116 Family=3D0x19 Model=3D0xa0 Stepping=3D0x02: Patch=3D0x0aa00212 Commit f2eb058afc57 ("linux-firmware: Update AMD cpu microcode") from the linux-firmware tree has binaries that meet the minimum required patch levels. Fixes: 7685665c390d ("perf/x86/amd/core: Add PerfMonV2 overflow handling") Reported-by: Jirka Hladky Signed-off-by: Breno Leitao [sandipan: add message to prompt users to update microcode] [sandipan: rework commit message and call out required microcode levels] Signed-off-by: Sandipan Das --- v1: https://lore.kernel.org/all/20230616115316.3652155-1-leitao@debian.org/ v2: - Use pr_warn_once() instead of WARN_ON_ONCE() to prompt users to update microcode - Rework commit message and add details of minimum required microcode patch levels. --- arch/x86/events/amd/core.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c index abadd5f23425..b04956cbd085 100644 --- a/arch/x86/events/amd/core.c +++ b/arch/x86/events/amd/core.c @@ -884,7 +884,7 @@ static int amd_pmu_v2_handle_irq(struct pt_regs *regs) struct hw_perf_event *hwc; struct perf_event *event; int handled =3D 0, idx; - u64 status, mask; + u64 reserved, status, mask; bool pmu_enabled; =20 /* @@ -909,6 +909,14 @@ static int amd_pmu_v2_handle_irq(struct pt_regs *regs) status &=3D ~GLOBAL_STATUS_LBRS_FROZEN; } =20 + reserved =3D status & ~amd_pmu_global_cntr_mask; + if (reserved) + pr_warn_once("Reserved PerfCntrGlobalStatus bits are set (0x%llx), pleas= e consider updating microcode\n", + reserved); + + /* Clear any reserved bits set by buggy microcode */ + status &=3D amd_pmu_global_cntr_mask; + for (idx =3D 0; idx < x86_pmu.num_counters; idx++) { if (!test_bit(idx, cpuc->active_mask)) continue; --=20 2.34.1