perf/x86/kvm: Avoid unnecessary work in guest filtering

KVM added a workaround for PEBS events leaking into guests with
commit:

  26a4f3c08de4 ("perf/x86: disable PEBS on a guest entry.")

This uses the VT entry/exit list to add an extra disable of the
PEBS_ENABLE MSR.

Intel also added a fix for this issue to microcode updates on
Haswell/Broadwell/Skylake.

It turns out using the MSR entry/exit list makes VM exits
significantly slower. The list is only needed for disabling
PEBS, because the GLOBAL_CTRL change gets optimized by
KVM into changing the VMCS.

Check for the microcode updates that have the microcode
fix for leaking PEBS, and disable the extra entry/exit list
entry for PEBS_ENABLE. In addition we always clear the
GLOBAL_CTRL for the PEBS counter while running in the guest,
which is enough to make them never fire at the wrong
side of the host/guest transition.

The overhead for VM exits with the filtering active with the patch is
reduced from 8% to 4%.

The microcode patch has already been merged into future platforms.
This patch is one-off thing. The quirks is used here.

For other old platforms which doesn't have microcode patch and quirks,
extra disable of the PEBS_ENABLE MSR is still required.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: bp@alien8.de
Link: https://lkml.kernel.org/r/1549319013-4522-2-git-send-email-kan.liang@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index daafb893449b6e1fb11c7f6b18e71d90da553909..8fe2afa9c81820901df24806d43a2898277f477d 100644 (file)
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -18,6 +18,7 @@
 #include <asm/hardirq.h>
 #include <asm/intel-family.h>
 #include <asm/apic.h>
+#include <asm/cpu_device_id.h>
 
 #include "../perf_event.h"
 
@@ -3206,16 +3207,27 @@ static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr)
        arr[0].msr = MSR_CORE_PERF_GLOBAL_CTRL;
        arr[0].host = x86_pmu.intel_ctrl & ~cpuc->intel_ctrl_guest_mask;
        arr[0].guest = x86_pmu.intel_ctrl & ~cpuc->intel_ctrl_host_mask;
-       /*
-        * If PMU counter has PEBS enabled it is not enough to disable counter
-        * on a guest entry since PEBS memory write can overshoot guest entry
-        * and corrupt guest memory. Disabling PEBS solves the problem.
-        */
-       arr[1].msr = MSR_IA32_PEBS_ENABLE;
-       arr[1].host = cpuc->pebs_enabled;
-       arr[1].guest = 0;
+       if (x86_pmu.flags & PMU_FL_PEBS_ALL)
+               arr[0].guest &= ~cpuc->pebs_enabled;
+       else
+               arr[0].guest &= ~(cpuc->pebs_enabled & PEBS_COUNTER_MASK);
+       *nr = 1;
+
+       if (x86_pmu.pebs && x86_pmu.pebs_no_isolation) {
+               /*
+                * If PMU counter has PEBS enabled it is not enough to
+                * disable counter on a guest entry since PEBS memory
+                * write can overshoot guest entry and corrupt guest
+                * memory. Disabling PEBS solves the problem.
+                *
+                * Don't do this if the CPU already enforces it.
+                */
+               arr[1].msr = MSR_IA32_PEBS_ENABLE;
+               arr[1].host = cpuc->pebs_enabled;
+               arr[1].guest = 0;
+               *nr = 2;
+       }
 
-       *nr = 2;
        return arr;
 }
 
@@ -3739,6 +3751,47 @@ static __init void intel_clovertown_quirk(void)
        x86_pmu.pebs_constraints = NULL;
 }
 
+static const struct x86_cpu_desc isolation_ucodes[] = {
+       INTEL_CPU_DESC(INTEL_FAM6_HASWELL_CORE,          3, 0x0000001f),
+       INTEL_CPU_DESC(INTEL_FAM6_HASWELL_ULT,           1, 0x0000001e),
+       INTEL_CPU_DESC(INTEL_FAM6_HASWELL_GT3E,          1, 0x00000015),
+       INTEL_CPU_DESC(INTEL_FAM6_HASWELL_X,             2, 0x00000037),
+       INTEL_CPU_DESC(INTEL_FAM6_HASWELL_X,             4, 0x0000000a),
+       INTEL_CPU_DESC(INTEL_FAM6_BROADWELL_CORE,        4, 0x00000023),
+       INTEL_CPU_DESC(INTEL_FAM6_BROADWELL_GT3E,        1, 0x00000014),
+       INTEL_CPU_DESC(INTEL_FAM6_BROADWELL_XEON_D,      2, 0x00000010),
+       INTEL_CPU_DESC(INTEL_FAM6_BROADWELL_XEON_D,      3, 0x07000009),
+       INTEL_CPU_DESC(INTEL_FAM6_BROADWELL_XEON_D,      4, 0x0f000009),
+       INTEL_CPU_DESC(INTEL_FAM6_BROADWELL_XEON_D,      5, 0x0e000002),
+       INTEL_CPU_DESC(INTEL_FAM6_BROADWELL_X,           2, 0x0b000014),
+       INTEL_CPU_DESC(INTEL_FAM6_SKYLAKE_X,             3, 0x00000021),
+       INTEL_CPU_DESC(INTEL_FAM6_SKYLAKE_X,             4, 0x00000000),
+       INTEL_CPU_DESC(INTEL_FAM6_SKYLAKE_MOBILE,        3, 0x0000007c),
+       INTEL_CPU_DESC(INTEL_FAM6_SKYLAKE_DESKTOP,       3, 0x0000007c),
+       INTEL_CPU_DESC(INTEL_FAM6_KABYLAKE_DESKTOP,      9, 0x0000004e),
+       INTEL_CPU_DESC(INTEL_FAM6_KABYLAKE_MOBILE,       9, 0x0000004e),
+       INTEL_CPU_DESC(INTEL_FAM6_KABYLAKE_MOBILE,      10, 0x0000004e),
+       INTEL_CPU_DESC(INTEL_FAM6_KABYLAKE_MOBILE,      11, 0x0000004e),
+       INTEL_CPU_DESC(INTEL_FAM6_KABYLAKE_MOBILE,      12, 0x0000004e),
+       INTEL_CPU_DESC(INTEL_FAM6_KABYLAKE_DESKTOP,     10, 0x0000004e),
+       INTEL_CPU_DESC(INTEL_FAM6_KABYLAKE_DESKTOP,     11, 0x0000004e),
+       INTEL_CPU_DESC(INTEL_FAM6_KABYLAKE_DESKTOP,     12, 0x0000004e),
+       INTEL_CPU_DESC(INTEL_FAM6_KABYLAKE_DESKTOP,     13, 0x0000004e),
+       {}
+};
+
+static void intel_check_pebs_isolation(void)
+{
+       x86_pmu.pebs_no_isolation = !x86_cpu_has_min_microcode_rev(isolation_ucodes);
+}
+
+static __init void intel_pebs_isolation_quirk(void)
+{
+       WARN_ON_ONCE(x86_pmu.check_microcode);
+       x86_pmu.check_microcode = intel_check_pebs_isolation;
+       intel_check_pebs_isolation();
+}
+
 static int intel_snb_pebs_broken(int cpu)
 {
        u32 rev = UINT_MAX; /* default to broken for unknown models */
@@ -4431,6 +4484,7 @@ __init int intel_pmu_init(void)
        case INTEL_FAM6_HASWELL_ULT:
        case INTEL_FAM6_HASWELL_GT3E:
                x86_add_quirk(intel_ht_bug);
+               x86_add_quirk(intel_pebs_isolation_quirk);
                x86_pmu.late_ack = true;
                memcpy(hw_cache_event_ids, hsw_hw_cache_event_ids, sizeof(hw_cache_event_ids));
                memcpy(hw_cache_extra_regs, hsw_hw_cache_extra_regs, sizeof(hw_cache_extra_regs));
@@ -4462,6 +4516,7 @@ __init int intel_pmu_init(void)
        case INTEL_FAM6_BROADWELL_XEON_D:
        case INTEL_FAM6_BROADWELL_GT3E:
        case INTEL_FAM6_BROADWELL_X:
+               x86_add_quirk(intel_pebs_isolation_quirk);
                x86_pmu.late_ack = true;
                memcpy(hw_cache_event_ids, hsw_hw_cache_event_ids, sizeof(hw_cache_event_ids));
                memcpy(hw_cache_extra_regs, hsw_hw_cache_extra_regs, sizeof(hw_cache_extra_regs));
@@ -4524,6 +4579,7 @@ __init int intel_pmu_init(void)
        case INTEL_FAM6_SKYLAKE_X:
        case INTEL_FAM6_KABYLAKE_MOBILE:
        case INTEL_FAM6_KABYLAKE_DESKTOP:
+               x86_add_quirk(intel_pebs_isolation_quirk);
                x86_pmu.late_ack = true;
                memcpy(hw_cache_event_ids, skl_hw_cache_event_ids, sizeof(hw_cache_event_ids));
                memcpy(hw_cache_extra_regs, skl_hw_cache_extra_regs, sizeof(hw_cache_extra_regs));

diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index e9acf1d2e7b28874a3708c21ea59f75591650312..10c99ce1feaddf5fa196bfbd385cbd02b55ef57a 100644 (file)
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1628,6 +1628,8 @@ void __init intel_ds_init(void)
        x86_pmu.bts  = boot_cpu_has(X86_FEATURE_BTS);
        x86_pmu.pebs = boot_cpu_has(X86_FEATURE_PEBS);
        x86_pmu.pebs_buffer_size = PEBS_BUFFER_SIZE;
+       if (x86_pmu.version <= 4)
+               x86_pmu.pebs_no_isolation = 1;
        if (x86_pmu.pebs) {
                char pebs_type = x86_pmu.intel_cap.pebs_trap ?  '+' : '-';
                int format = x86_pmu.intel_cap.pebs_format;

diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index 78d7b7031bfccb8ec2dbcd7de6e54a29fd1365ce..dea716e1f713ea158e328fce96c3c20084e32d56 100644 (file)
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -601,13 +601,14 @@ struct x86_pmu {
        /*
         * Intel DebugStore bits
         */
-       unsigned int    bts             :1,
-                       bts_active      :1,
-                       pebs            :1,
-                       pebs_active     :1,
-                       pebs_broken     :1,
-                       pebs_prec_dist  :1,
-                       pebs_no_tlb     :1;
+       unsigned int    bts                     :1,
+                       bts_active              :1,
+                       pebs                    :1,
+                       pebs_active             :1,
+                       pebs_broken             :1,
+                       pebs_prec_dist          :1,
+                       pebs_no_tlb             :1,
+                       pebs_no_isolation       :1;
        int             pebs_record_size;
        int             pebs_buffer_size;
        void            (*drain_pebs)(struct pt_regs *regs);