On Mon, Oct 21, 2024, Manali Shukla wrote:
From: Manali Shukla Manali.Shukla@amd.com
The interface is used to read the data values of a specified vcpu stat from the currenly available binary stats interface.
Add a concatenation trickery to trigger compiler error if the stat doesn't exist, so that it is not possible to pass a per-VM stat into vcpu_get_stat().
Suggested-by: Sean Christopherson seanjc@google.com Signed-off-by: Manali Shukla Manali.Shukla@amd.com
.../testing/selftests/kvm/include/kvm_util.h | 52 +++++++++++++++++++ .../kvm/include/x86_64/kvm_util_arch.h | 36 +++++++++++++ tools/testing/selftests/kvm/lib/kvm_util.c | 40 ++++++++++++++ 3 files changed, 128 insertions(+)
diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h index bc7c242480d6..5dd3acf174f8 100644 --- a/tools/testing/selftests/kvm/include/kvm_util.h +++ b/tools/testing/selftests/kvm/include/kvm_util.h @@ -531,6 +531,14 @@ void read_stat_data(int stats_fd, struct kvm_stats_header *header, struct kvm_stats_desc *desc, uint64_t *data, size_t max_elements); +#define DEFINE_CHECK_STAT(type, stat) \ +static inline int check_##type##_##stat##_exists(void) \ +{ \
- return 1; \
+} \
+#define STAT_EXISTS(type, stat) (check_##type##_##stat##_exists())
This is all unnecessary complicated. To trigger a compilation error, the set of knnown stats just needs to be defined as _something_ and then referenced. There's no need for layers of macros and a function for each stat. The fact that a stat is defined is proof of its existence.
void __vm_get_stat(struct kvm_vm *vm, const char *stat_name, uint64_t *data, size_t max_elements); @@ -542,6 +550,50 @@ static inline uint64_t vm_get_stat(struct kvm_vm *vm, const char *stat_name) return data; } +#define DEFINE_GENERIC_VCPU_STAT \
- DEFINE_CHECK_STAT(vcpu, halt_successfull_poll) \
- DEFINE_CHECK_STAT(vcpu, halt_attempted_poll) \
- DEFINE_CHECK_STAT(vcpu, halt_poll_invalid) \
- DEFINE_CHECK_STAT(vcpu, halt_wakeup) \
- DEFINE_CHECK_STAT(vcpu, halt_poll_success_ns) \
- DEFINE_CHECK_STAT(vcpu, halt_poll_fail_ns) \
- DEFINE_CHECK_STAT(vcpu, halt_wait_ns) \
- DEFINE_CHECK_STAT(vcpu, halt_poll_success_hist) \
- DEFINE_CHECK_STAT(vcpu, halt_poll_fail_hist) \
- DEFINE_CHECK_STAT(vcpu, halt_wait_hist) \
- DEFINE_CHECK_STAT(vcpu, blocking) \
+/*
- Define a default empty macro for architectures which do not specify
- arch specific vcpu stats
- */
+#ifndef DEFINE_ARCH_VCPU_STAT +#define DEFINE_ARCH_VCPU_STAT +#endif
+DEFINE_GENERIC_VCPU_STAT
There's also no need to define macros in arch code just to expand them in common code. Add simple macros in kvm_util_types.h and this goes away.
+DEFINE_ARCH_VCPU_STAT
+#undef DEFINE_CHECK_STAT +#undef DEFINE_GENERIC_VCPU_STAT +#undef DEFINE_ARCH_VCPU_STAT
+void __vcpu_get_stat(struct kvm_vcpu *vcpu, const char *stat_name, uint64_t *data,
size_t max_elements);+#define vcpu_get_stat(vcpu, stat_name) \ +({ \
- uint64_t data; \
\- STAT_EXISTS(vcpu, stat_name); \
- __vcpu_get_stat(vcpu, #stat_name, &data, 1); \
- data; \
+}) \
+#undef DEFINE_CHECK_STAT +#undef DEFINE_GENERIC_VCPU_STAT
...
+void __vcpu_get_stat(struct kvm_vcpu *vcpu, const char *stat_name, uint64_t *data,
size_t max_elements)+{
- int vcpu_stats_fd;
- struct kvm_stats_header header;
- struct kvm_stats_desc *desc, *t_desc;
- size_t size_desc;
- int i;
- vcpu_stats_fd = vcpu_get_stats_fd(vcpu);
- read_stats_header(vcpu_stats_fd, &header);
- desc = read_stats_descriptors(vcpu_stats_fd, &header);
- size_desc = get_stats_descriptor_size(&header);
- for (i = 0; i < header.num_desc; ++i) {
t_desc = (void *)desc + (i * size_desc);if (strcmp(t_desc->name, stat_name))continue;read_stat_data(vcpu_stats_fd, &header, t_desc,data, max_elements);break;- }
+}
This is copy-pasted nearly verbatim from the VM-scoped code. It even has the same bugs (doesn't assert the stat exists), along with new bugs (leaks the fd and header).
It takes a bit of work, but not _that_ much work, to genericize the VM-scoped infrastructure and reuse it for vCPU-scoped stats.