linux-kernel - [tip: perf/urgent] perf/x86/intel: Save/restore cpuc->active_pebs_data

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Date:   Tue, 23 May 2023 08:15:46 -0000
From:   "tip-bot2 for Like Xu" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Like Xu <likexu@...cent.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Kan Liang <kan.liang@...ux.intel.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: perf/urgent] perf/x86/intel: Save/restore
 cpuc->active_pebs_data_cfg when using guest PEBS

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     3c845304d2d723f20d5b91fef5d133ff94825d76
Gitweb:        https://git.kernel.org/tip/3c845304d2d723f20d5b91fef5d133ff94825d76
Author:        Like Xu <likexu@...cent.com>
AuthorDate:    Wed, 17 May 2023 21:38:08 +08:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Tue, 23 May 2023 10:01:13 +02:00

perf/x86/intel: Save/restore cpuc->active_pebs_data_cfg when using guest PEBS

After commit b752ea0c28e3 ("perf/x86/intel/ds: Flush PEBS DS when changing
PEBS_DATA_CFG"), the cpuc->pebs_data_cfg may save some bits that are not
supported by real hardware, such as PEBS_UPDATE_DS_SW. This would cause
the VMX hardware MSR switching mechanism to save/restore invalid values
for PEBS_DATA_CFG MSR, thus crashing the host when PEBS is used for guest.
Fix it by using the active host value from cpuc->active_pebs_data_cfg.

Fixes: b752ea0c28e3 ("perf/x86/intel/ds: Flush PEBS DS when changing PEBS_DATA_CFG")
Signed-off-by: Like Xu <likexu@...cent.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Kan Liang <kan.liang@...ux.intel.com>
Link: https://lore.kernel.org/r/20230517133808.67885-1-likexu@tencent.com
---
 arch/x86/events/intel/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 070cc4e..89b9c1c 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4074,7 +4074,7 @@ static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr, void *data)
 	if (x86_pmu.intel_cap.pebs_baseline) {
 		arr[(*nr)++] = (struct perf_guest_switch_msr){
 			.msr = MSR_PEBS_DATA_CFG,
-			.host = cpuc->pebs_data_cfg,
+			.host = cpuc->active_pebs_data_cfg,
 			.guest = kvm_pmu->pebs_data_cfg,
 		};
 	}