Mailing List Archive

[PATCH] KVM: x86: Add fixed counters to PMU filter
From: ehankland <ehankland@google.com>

Updates KVM_CAP_PMU_EVENT_FILTER so it can also whitelist or blacklist
fixed counters.

Signed-off-by: ehankland <ehankland@google.com>
---
Documentation/virtual/kvm/api.txt | 13 ++++++++-----
arch/x86/include/uapi/asm/kvm.h | 9 ++++++---
arch/x86/kvm/pmu.c | 30 +++++++++++++++++++++++++-----
3 files changed, 39 insertions(+), 13 deletions(-)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 2cd6250b2896..96bcf1aa1931 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -4090,17 +4090,20 @@ Parameters: struct kvm_pmu_event_filter (in)
Returns: 0 on success, -1 on error

struct kvm_pmu_event_filter {
- __u32 action;
- __u32 nevents;
- __u64 events[0];
+ __u32 action;
+ __u32 nevents;
+ __u32 fixed_counter_bitmap;
+ __u32 flags;
+ __u32 pad[4];
+ __u64 events[0];
};

This ioctl restricts the set of PMU events that the guest can program.
The argument holds a list of events which will be allowed or denied.
The eventsel+umask of each event the guest attempts to program is compared
against the events field to determine whether the guest should have access.
-This only affects general purpose counters; fixed purpose counters can
-be disabled by changing the perfmon CPUID leaf.
+The events field only controls general purpose counters; fixed purpose
+counters are controlled by the fixed_counter_bitmap.

Valid values for 'action':
#define KVM_PMU_EVENT_ALLOW 0
diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index e901b0ab116f..503d3f42da16 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -435,9 +435,12 @@ struct kvm_nested_state {

/* for KVM_CAP_PMU_EVENT_FILTER */
struct kvm_pmu_event_filter {
- __u32 action;
- __u32 nevents;
- __u64 events[0];
+ __u32 action;
+ __u32 nevents;
+ __u32 fixed_counter_bitmap;
+ __u32 flags;
+ __u32 pad[4];
+ __u64 events[0];
};

#define KVM_PMU_EVENT_ALLOW 0
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index aa5a2597305a..ae5cd1b02086 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -19,8 +19,8 @@
#include "lapic.h"
#include "pmu.h"

-/* This keeps the total size of the filter under 4k. */
-#define KVM_PMU_EVENT_FILTER_MAX_EVENTS 63
+/* This is enough to filter the vast majority of currently defined events. */
+#define KVM_PMU_EVENT_FILTER_MAX_EVENTS 300

/* NOTE:
* - Each perf counter is defined as "struct kvm_pmc";
@@ -206,12 +206,25 @@ void reprogram_fixed_counter(struct kvm_pmc *pmc, u8 ctrl, int idx)
{
unsigned en_field = ctrl & 0x3;
bool pmi = ctrl & 0x8;
+ struct kvm_pmu_event_filter *filter;
+ struct kvm *kvm = pmc->vcpu->kvm;
+

pmc_stop_counter(pmc);

if (!en_field || !pmc_is_enabled(pmc))
return;

+ filter = srcu_dereference(kvm->arch.pmu_event_filter, &kvm->srcu);
+ if (filter) {
+ if (filter->action == KVM_PMU_EVENT_DENY &&
+ test_bit(idx, (ulong *)&filter->fixed_counter_bitmap))
+ return;
+ if (filter->action == KVM_PMU_EVENT_ALLOW &&
+ !test_bit(idx, (ulong *)&filter->fixed_counter_bitmap))
+ return;
+ }
+
pmc_reprogram_counter(pmc, PERF_TYPE_HARDWARE,
kvm_x86_ops->pmu_ops->find_fixed_event(idx),
!(en_field & 0x2), /* exclude user */
@@ -376,7 +389,7 @@ int kvm_vm_ioctl_set_pmu_event_filter(struct kvm *kvm, void __user *argp)
{
struct kvm_pmu_event_filter tmp, *filter;
size_t size;
- int r;
+ int r, i;

if (copy_from_user(&tmp, argp, sizeof(tmp)))
return -EFAULT;
@@ -385,6 +398,13 @@ int kvm_vm_ioctl_set_pmu_event_filter(struct kvm *kvm, void __user *argp)
tmp.action != KVM_PMU_EVENT_DENY)
return -EINVAL;

+ if (tmp.flags != 0)
+ return -EINVAL;
+
+ for (i = 0; i < ARRAY_SIZE(tmp.pad); i++)
+ if (tmp.pad[i] != 0)
+ return -EINVAL;
+
if (tmp.nevents > KVM_PMU_EVENT_FILTER_MAX_EVENTS)
return -E2BIG;

@@ -406,8 +426,8 @@ int kvm_vm_ioctl_set_pmu_event_filter(struct kvm *kvm, void __user *argp)
mutex_unlock(&kvm->lock);

synchronize_srcu_expedited(&kvm->srcu);
- r = 0;
+ r = 0;
cleanup:
kfree(filter);
- return r;
+ return r;
}
Re: [PATCH] KVM: x86: Add fixed counters to PMU filter [ In reply to ]
On 07/19/2019 02:38 AM, Eric Hankland wrote:
> From: ehankland <ehankland@google.com>
>
> Updates KVM_CAP_PMU_EVENT_FILTER so it can also whitelist or blacklist
> fixed counters.
>
> Signed-off-by: ehankland <ehankland@google.com>
> ---
> Documentation/virtual/kvm/api.txt | 13 ++++++++-----
> arch/x86/include/uapi/asm/kvm.h | 9 ++++++---
> arch/x86/kvm/pmu.c | 30 +++++++++++++++++++++++++-----
> 3 files changed, 39 insertions(+), 13 deletions(-)
>
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 2cd6250b2896..96bcf1aa1931 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -4090,17 +4090,20 @@ Parameters: struct kvm_pmu_event_filter (in)
> Returns: 0 on success, -1 on error
>
> struct kvm_pmu_event_filter {
> - __u32 action;
> - __u32 nevents;
> - __u64 events[0];
> + __u32 action;
> + __u32 nevents;
> + __u32 fixed_counter_bitmap;
> + __u32 flags;
> + __u32 pad[4];
> + __u64 events[0];
> };
>
> This ioctl restricts the set of PMU events that the guest can program.
> The argument holds a list of events which will be allowed or denied.
> The eventsel+umask of each event the guest attempts to program is compared
> against the events field to determine whether the guest should have access.
> -This only affects general purpose counters; fixed purpose counters can
> -be disabled by changing the perfmon CPUID leaf.
> +The events field only controls general purpose counters; fixed purpose
> +counters are controlled by the fixed_counter_bitmap.
>
> Valid values for 'action':
> #define KVM_PMU_EVENT_ALLOW 0
> diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
> index e901b0ab116f..503d3f42da16 100644
> --- a/arch/x86/include/uapi/asm/kvm.h
> +++ b/arch/x86/include/uapi/asm/kvm.h
> @@ -435,9 +435,12 @@ struct kvm_nested_state {
>
> /* for KVM_CAP_PMU_EVENT_FILTER */
> struct kvm_pmu_event_filter {
> - __u32 action;
> - __u32 nevents;
> - __u64 events[0];
> + __u32 action;
> + __u32 nevents;
> + __u32 fixed_counter_bitmap;
> + __u32 flags;
> + __u32 pad[4];
> + __u64 events[0];
> };
>
> #define KVM_PMU_EVENT_ALLOW 0
> diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
> index aa5a2597305a..ae5cd1b02086 100644
> --- a/arch/x86/kvm/pmu.c
> +++ b/arch/x86/kvm/pmu.c
> @@ -19,8 +19,8 @@
> #include "lapic.h"
> #include "pmu.h"
>
> -/* This keeps the total size of the filter under 4k. */
> -#define KVM_PMU_EVENT_FILTER_MAX_EVENTS 63
> +/* This is enough to filter the vast majority of currently defined events. */
> +#define KVM_PMU_EVENT_FILTER_MAX_EVENTS 300
>
> /* NOTE:
> * - Each perf counter is defined as "struct kvm_pmc";
> @@ -206,12 +206,25 @@ void reprogram_fixed_counter(struct kvm_pmc *pmc, u8 ctrl, int idx)
> {
> unsigned en_field = ctrl & 0x3;
> bool pmi = ctrl & 0x8;
> + struct kvm_pmu_event_filter *filter;
> + struct kvm *kvm = pmc->vcpu->kvm;
> +

unnecessary white space here, other part looks good to me.

Reviewed-by: Wei Wang <wei.w.wang@intel.com>

Best,
Wei
Re: [PATCH] KVM: x86: Add fixed counters to PMU filter [ In reply to ]
On 18/07/19 20:38, Eric Hankland wrote:
> From: ehankland <ehankland@google.com>
>
> Updates KVM_CAP_PMU_EVENT_FILTER so it can also whitelist or blacklist
> fixed counters.
>
> Signed-off-by: ehankland <ehankland@google.com>

Very nice, thanks.

There's no need to check the padding for zero (flags can be defined to
give specific meanings in the future to the padding fields), I removed
that loop and queued the patch.

Paolo

> ---
> Documentation/virtual/kvm/api.txt | 13 ++++++++-----
> arch/x86/include/uapi/asm/kvm.h | 9 ++++++---
> arch/x86/kvm/pmu.c | 30 +++++++++++++++++++++++++-----
> 3 files changed, 39 insertions(+), 13 deletions(-)
>
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 2cd6250b2896..96bcf1aa1931 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -4090,17 +4090,20 @@ Parameters: struct kvm_pmu_event_filter (in)
> Returns: 0 on success, -1 on error
>
> struct kvm_pmu_event_filter {
> - __u32 action;
> - __u32 nevents;
> - __u64 events[0];
> + __u32 action;
> + __u32 nevents;
> + __u32 fixed_counter_bitmap;
> + __u32 flags;
> + __u32 pad[4];
> + __u64 events[0];
> };
>
> This ioctl restricts the set of PMU events that the guest can program.
> The argument holds a list of events which will be allowed or denied.
> The eventsel+umask of each event the guest attempts to program is compared
> against the events field to determine whether the guest should have access.
> -This only affects general purpose counters; fixed purpose counters can
> -be disabled by changing the perfmon CPUID leaf.
> +The events field only controls general purpose counters; fixed purpose
> +counters are controlled by the fixed_counter_bitmap.
>
> Valid values for 'action':
> #define KVM_PMU_EVENT_ALLOW 0
> diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
> index e901b0ab116f..503d3f42da16 100644
> --- a/arch/x86/include/uapi/asm/kvm.h
> +++ b/arch/x86/include/uapi/asm/kvm.h
> @@ -435,9 +435,12 @@ struct kvm_nested_state {
>
> /* for KVM_CAP_PMU_EVENT_FILTER */
> struct kvm_pmu_event_filter {
> - __u32 action;
> - __u32 nevents;
> - __u64 events[0];
> + __u32 action;
> + __u32 nevents;
> + __u32 fixed_counter_bitmap;
> + __u32 flags;
> + __u32 pad[4];
> + __u64 events[0];
> };
>
> #define KVM_PMU_EVENT_ALLOW 0
> diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
> index aa5a2597305a..ae5cd1b02086 100644
> --- a/arch/x86/kvm/pmu.c
> +++ b/arch/x86/kvm/pmu.c
> @@ -19,8 +19,8 @@
> #include "lapic.h"
> #include "pmu.h"
>
> -/* This keeps the total size of the filter under 4k. */
> -#define KVM_PMU_EVENT_FILTER_MAX_EVENTS 63
> +/* This is enough to filter the vast majority of currently defined events. */
> +#define KVM_PMU_EVENT_FILTER_MAX_EVENTS 300
>
> /* NOTE:
> * - Each perf counter is defined as "struct kvm_pmc";
> @@ -206,12 +206,25 @@ void reprogram_fixed_counter(struct kvm_pmc *pmc, u8 ctrl, int idx)
> {
> unsigned en_field = ctrl & 0x3;
> bool pmi = ctrl & 0x8;
> + struct kvm_pmu_event_filter *filter;
> + struct kvm *kvm = pmc->vcpu->kvm;
> +
>
> pmc_stop_counter(pmc);
>
> if (!en_field || !pmc_is_enabled(pmc))
> return;
>
> + filter = srcu_dereference(kvm->arch.pmu_event_filter, &kvm->srcu);
> + if (filter) {
> + if (filter->action == KVM_PMU_EVENT_DENY &&
> + test_bit(idx, (ulong *)&filter->fixed_counter_bitmap))
> + return;
> + if (filter->action == KVM_PMU_EVENT_ALLOW &&
> + !test_bit(idx, (ulong *)&filter->fixed_counter_bitmap))
> + return;
> + }
> +
> pmc_reprogram_counter(pmc, PERF_TYPE_HARDWARE,
> kvm_x86_ops->pmu_ops->find_fixed_event(idx),
> !(en_field & 0x2), /* exclude user */
> @@ -376,7 +389,7 @@ int kvm_vm_ioctl_set_pmu_event_filter(struct kvm *kvm, void __user *argp)
> {
> struct kvm_pmu_event_filter tmp, *filter;
> size_t size;
> - int r;
> + int r, i;
>
> if (copy_from_user(&tmp, argp, sizeof(tmp)))
> return -EFAULT;
> @@ -385,6 +398,13 @@ int kvm_vm_ioctl_set_pmu_event_filter(struct kvm *kvm, void __user *argp)
> tmp.action != KVM_PMU_EVENT_DENY)
> return -EINVAL;
>
> + if (tmp.flags != 0)
> + return -EINVAL;
> +
> + for (i = 0; i < ARRAY_SIZE(tmp.pad); i++)
> + if (tmp.pad[i] != 0)
> + return -EINVAL;
> +
> if (tmp.nevents > KVM_PMU_EVENT_FILTER_MAX_EVENTS)
> return -E2BIG;
>
> @@ -406,8 +426,8 @@ int kvm_vm_ioctl_set_pmu_event_filter(struct kvm *kvm, void __user *argp)
> mutex_unlock(&kvm->lock);
>
> synchronize_srcu_expedited(&kvm->srcu);
> - r = 0;
> + r = 0;
> cleanup:
> kfree(filter);
> - return r;
> + return r;
> }
>