linux-kernel - [tip: perf/core] perf/x86/amd/core: Fix reloading events for SVM

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Date:   Thu, 19 May 2022 21:56:59 -0000
From:   "tip-bot2 for Sandipan Das" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Like Xu <likexu@...cent.com>, Sandipan Das <sandipan.das@....com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: perf/core] perf/x86/amd/core: Fix reloading events for SVM

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

Commit-ID:     bae19fdd7e9e759580ac4693d2df3bc23ab415d7
Gitweb:        https://git.kernel.org/tip/bae19fdd7e9e759580ac4693d2df3bc23ab415d7
Author:        Sandipan Das <sandipan.das@....com>
AuthorDate:    Wed, 18 May 2022 14:13:27 +05:30
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Thu, 19 May 2022 23:46:14 +02:00

perf/x86/amd/core: Fix reloading events for SVM

Commit 1018faa6cf23 ("perf/x86/kvm: Fix Host-Only/Guest-Only
counting with SVM disabled") addresses an issue in which the
Host-Only bit in the counter control registers needs to be
masked off when SVM is not enabled.

The events need to be reloaded whenever SVM is enabled or
disabled for a CPU and this requires the PERF_CTL registers
to be reprogrammed using {enable,disable}_all(). However,
PerfMonV2 variants of these functions do not reprogram the
PERF_CTL registers. Hence, the legacy enable_all() function
should also be called.

Fixes: 9622e67e3980 ("perf/x86/amd/core: Add PerfMonV2 counter control")
Reported-by: Like Xu <likexu@...cent.com>
Signed-off-by: Sandipan Das <sandipan.das@....com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/20220518084327.464005-1-sandipan.das@amd.com
---
 arch/x86/events/amd/core.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index 3eee59c..9ac3718 100644
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -1472,6 +1472,24 @@ __init int amd_pmu_init(void)
 	return 0;
 }
 
+static inline void amd_pmu_reload_virt(void)
+{
+	if (x86_pmu.version >= 2) {
+		/*
+		 * Clear global enable bits, reprogram the PERF_CTL
+		 * registers with updated perf_ctr_virt_mask and then
+		 * set global enable bits once again
+		 */
+		amd_pmu_v2_disable_all();
+		amd_pmu_enable_all(0);
+		amd_pmu_v2_enable_all(0);
+		return;
+	}
+
+	amd_pmu_disable_all();
+	amd_pmu_enable_all(0);
+}
+
 void amd_pmu_enable_virt(void)
 {
 	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
@@ -1479,8 +1497,7 @@ void amd_pmu_enable_virt(void)
 	cpuc->perf_ctr_virt_mask = 0;
 
 	/* Reload all events */
-	amd_pmu_disable_all();
-	x86_pmu_enable_all(0);
+	amd_pmu_reload_virt();
 }
 EXPORT_SYMBOL_GPL(amd_pmu_enable_virt);
 
@@ -1497,7 +1514,6 @@ void amd_pmu_disable_virt(void)
 	cpuc->perf_ctr_virt_mask = AMD64_EVENTSEL_HOSTONLY;
 
 	/* Reload all events */
-	amd_pmu_disable_all();
-	x86_pmu_enable_all(0);
+	amd_pmu_reload_virt();
 }
 EXPORT_SYMBOL_GPL(amd_pmu_disable_virt);