On Tue, May 28, 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.
Signed-off-by: Manali Shukla Manali.Shukla@amd.com
.../kvm/include/kvm_arch_vcpu_states.h | 49 +++++++++++++++++++ .../testing/selftests/kvm/include/kvm_util.h | 34 +++++++++++++ tools/testing/selftests/kvm/lib/kvm_util.c | 32 ++++++++++++ 3 files changed, 115 insertions(+) create mode 100644 tools/testing/selftests/kvm/include/kvm_arch_vcpu_states.h
diff --git a/tools/testing/selftests/kvm/include/kvm_arch_vcpu_states.h b/tools/testing/selftests/kvm/include/kvm_arch_vcpu_states.h new file mode 100644 index 000000000000..755ff7de53d9 --- /dev/null +++ b/tools/testing/selftests/kvm/include/kvm_arch_vcpu_states.h @@ -0,0 +1,49 @@ +/* SPDX-License-Identifier: GPL-2.0 */
+/*
- Arch-specific stats are added to the kvm_arch_vcpu_states.h. Sequence
- of arch-specific vcpu_stat_type should be same as they are declared in
- arch-specific kvm_vcpu_stat.
- */
+#ifdef __x86_64__
This is backwards. If you want arch specific stats, put it them in an arch specific header.
+#define KVM_X86_VCPU_STATE(x) KVM_VCPU_STATE(x)
+KVM_X86_VCPU_STATE(PF_TAKEN)
I'm pretty sure you want KVM_VCPU_STAT, KVM_X86_VCPU_STAT, kvm_arch_vcpu_states.h, etc.
+KVM_X86_VCPU_STATE(PF_FIXED)
...
+/*
- Ensure that the sequence of the enum vcpu_stat_types matches the order of
- kvm_vcpu_stats_desc[]. Otherwise, vcpu_get_stat() may return incorrect data
- because __vcpu_get_stat() uses the enum type as an index to get the
- descriptor for a given stat and then uses read_stat_data() to get the stats
- from the descriptor.
This isn't maintainable. Unless I'm missing something, the _order_ of KVM's stats isn't ABI, and blindly reading an entry and hoping its the right one is doomed to fail.
I don't see any reason whatsoever to diverge from the core functionality of __vm_get_stat(). The only difference should be the origin of the stats file and header.
I do see a lot of room for improvement, but that can and should be done for both VM and vCPU stats. E.g. provide an API (and a container/struct?) to get a direct pointer to stat so that selftests don't have to walk all descriptors when they're reading the same stat over and over.
And to detect typos at compile time, {vcpu,vm}_get_stat() could either play macro games or use enums and array to detect usage of a stat that doesn't exist. E.g.
static inline uint64_t vm_get_stat(struct kvm_vm *vm, int stat) { uint64_t data;
__vm_get_stat(vm, kvm_vm_stats[stat], &data, 1); return data; }
or
#define vm_get_stat(vm, stat) \ ({ \ uin64_t __data; \ \ <concatenation trickery to trigger compiler error if the stat doesn't exit> __vm_get_stat(vm, #stat, &data, 1); \ data; \ })
I'd probably vote for macro games, e.g. so that it's all but impossible to pass a per-VM stat into vcpu_get_stat(), and vice versa.