Extend the kvm_get_feature_msr function to cover also KVM_GET_MSR_FEATURE_INDEX_LIST.
Signed-off-by: Emanuele Giuseppe Esposito eesposit@redhat.com --- tools/testing/selftests/kvm/lib/x86_64/processor.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c index a8906e60a108..3eaa6b0172a9 100644 --- a/tools/testing/selftests/kvm/lib/x86_64/processor.c +++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c @@ -688,13 +688,20 @@ uint64_t kvm_get_feature_msr(uint64_t msr_index) struct kvm_msr_entry entry; } buffer = {}; int r, kvm_fd; + struct kvm_msr_list features_list;
buffer.header.nmsrs = 1; buffer.entry.index = msr_index; + features_list.nmsrs = 1; + kvm_fd = open(KVM_DEV_PATH, O_RDONLY); if (kvm_fd < 0) exit(KSFT_SKIP);
+ r = ioctl(kvm_fd, KVM_GET_MSR_FEATURE_INDEX_LIST, &features_list); + TEST_ASSERT(r < 0 && r != -E2BIG, "KVM_GET_MSR_FEATURE_INDEX_LIST IOCTL failed,\n" + " rc: %i errno: %i", r, errno); + r = ioctl(kvm_fd, KVM_GET_MSRS, &buffer.header); TEST_ASSERT(r == 1, "KVM_GET_MSRS IOCTL failed,\n" " rc: %i errno: %i", r, errno);
On 17/03/21 08:45, Emanuele Giuseppe Esposito wrote:
- struct kvm_msr_list features_list;
buffer.header.nmsrs = 1; buffer.entry.index = msr_index;
- features_list.nmsrs = 1;
- kvm_fd = open(KVM_DEV_PATH, O_RDONLY); if (kvm_fd < 0) exit(KSFT_SKIP);
- r = ioctl(kvm_fd, KVM_GET_MSR_FEATURE_INDEX_LIST, &features_list);
- TEST_ASSERT(r < 0 && r != -E2BIG, "KVM_GET_MSR_FEATURE_INDEX_LIST IOCTL failed,\n"
" rc: %i errno: %i", r, errno);
Careful: because this has nsmrs == 1, you are overwriting an u32 of the stack after struct kvm_msr_list. You need to use your own struct similar to what is done with "buffer.header" and "buffer.entry".
r = ioctl(kvm_fd, KVM_GET_MSRS, &buffer.header); TEST_ASSERT(r == 1, "KVM_GET_MSRS IOCTL failed,\n" " rc: %i errno: %i", r, errno);
More in general, this is not a test, but rather a library function used to read a single MSR.
If you would like to add a test for KVM_GET_MSR_FEATURE_INDEX_LIST that would be very welcome. That would be a new executable. Looking at the logic for the ioctl, the main purpose of the test should be:
- check that if features_list.nmsrs is too small it will set the nmsrs field and return -E2BIG.
- check that all MSRs returned by KVM_GET_MSR_FEATURE_INDEX_LIST can be accessed with KVM_GET_MSRS
So something like this:
set nmsrs to 0 and try the ioctl check that it returns -E2BIG and has changed nmsrs if nmsrs != 1 { set nmsrs to 1 and try the ioctl again check that it returns -E2BIG } malloc a buffer with room for struct kvm_msr_list and nmsrs indices set nmsrs in the malloc-ed buffer and try the ioctl again for each index invoke kvm_get_feature_msr to read it
(The test should also be skipped if KVM does not expose the KVM_CAP_GET_MSR_FEATURES capability).
Thanks,
Paolo
On 17/03/2021 11:49, Paolo Bonzini wrote:
On 17/03/21 08:45, Emanuele Giuseppe Esposito wrote:
+ struct kvm_msr_list features_list; buffer.header.nmsrs = 1; buffer.entry.index = msr_index; + features_list.nmsrs = 1;
kvm_fd = open(KVM_DEV_PATH, O_RDONLY); if (kvm_fd < 0) exit(KSFT_SKIP); + r = ioctl(kvm_fd, KVM_GET_MSR_FEATURE_INDEX_LIST, &features_list); + TEST_ASSERT(r < 0 && r != -E2BIG, "KVM_GET_MSR_FEATURE_INDEX_LIST IOCTL failed,\n" + " rc: %i errno: %i", r, errno);
Careful: because this has nsmrs == 1, you are overwriting an u32 of the stack after struct kvm_msr_list. You need to use your own struct similar to what is done with "buffer.header" and "buffer.entry".
r = ioctl(kvm_fd, KVM_GET_MSRS, &buffer.header); TEST_ASSERT(r == 1, "KVM_GET_MSRS IOCTL failed,\n" " rc: %i errno: %i", r, errno);
More in general, this is not a test, but rather a library function used to read a single MSR.
If you would like to add a test for KVM_GET_MSR_FEATURE_INDEX_LIST that would be very welcome. That would be a new executable. Looking at the logic for the ioctl, the main purpose of the test should be:
- check that if features_list.nmsrs is too small it will set the nmsrs
field and return -E2BIG.
- check that all MSRs returned by KVM_GET_MSR_FEATURE_INDEX_LIST can be
accessed with KVM_GET_MSRS
So something like this:
set nmsrs to 0 and try the ioctl check that it returns -E2BIG and has changed nmsrs if nmsrs != 1 { set nmsrs to 1 and try the ioctl again check that it returns -E2BIG } malloc a buffer with room for struct kvm_msr_list and nmsrs indices set nmsrs in the malloc-ed buffer and try the ioctl again for each index invoke kvm_get_feature_msr to read it
(The test should also be skipped if KVM does not expose the KVM_CAP_GET_MSR_FEATURES capability).
Thank you for the feedback, the title is indeed a little bit misleading. My idea in this patch was to just add an additional check to all usages of KVM_GET_MSRS, since KVM_GET_MSR_FEATURE_INDEX_LIST is used only to probe host capabilities and processor features. But you are right, a separate test would be better.
Thank you, Emanuele
On Wed, Mar 17, 2021 at 12:25:52PM +0100, Emanuele Giuseppe Esposito wrote:
On 17/03/2021 11:49, Paolo Bonzini wrote:
On 17/03/21 08:45, Emanuele Giuseppe Esposito wrote:
+ struct kvm_msr_list features_list; buffer.header.nmsrs = 1; buffer.entry.index = msr_index; + features_list.nmsrs = 1;
kvm_fd = open(KVM_DEV_PATH, O_RDONLY); if (kvm_fd < 0) exit(KSFT_SKIP); + r = ioctl(kvm_fd, KVM_GET_MSR_FEATURE_INDEX_LIST, &features_list); + TEST_ASSERT(r < 0 && r != -E2BIG, "KVM_GET_MSR_FEATURE_INDEX_LIST IOCTL failed,\n" + " rc: %i errno: %i", r, errno);
Careful: because this has nsmrs == 1, you are overwriting an u32 of the stack after struct kvm_msr_list. You need to use your own struct similar to what is done with "buffer.header" and "buffer.entry".
r = ioctl(kvm_fd, KVM_GET_MSRS, &buffer.header); TEST_ASSERT(r == 1, "KVM_GET_MSRS IOCTL failed,\n" " rc: %i errno: %i", r, errno);
More in general, this is not a test, but rather a library function used to read a single MSR.
If you would like to add a test for KVM_GET_MSR_FEATURE_INDEX_LIST that would be very welcome. That would be a new executable. Looking at the logic for the ioctl, the main purpose of the test should be:
- check that if features_list.nmsrs is too small it will set the nmsrs
field and return -E2BIG.
- check that all MSRs returned by KVM_GET_MSR_FEATURE_INDEX_LIST can be
accessed with KVM_GET_MSRS
So something like this:
set nmsrs to 0 and try the ioctl check that it returns -E2BIG and has changed nmsrs if nmsrs != 1 { set nmsrs to 1 and try the ioctl again check that it returns -E2BIG } malloc a buffer with room for struct kvm_msr_list and nmsrs indices set nmsrs in the malloc-ed buffer and try the ioctl again for each index invoke kvm_get_feature_msr to read it
(The test should also be skipped if KVM does not expose the KVM_CAP_GET_MSR_FEATURES capability).
Thank you for the feedback, the title is indeed a little bit misleading. My idea in this patch was to just add an additional check to all usages of KVM_GET_MSRS, since KVM_GET_MSR_FEATURE_INDEX_LIST is used only to probe host capabilities and processor features. But you are right, a separate test would be better.
Hi Emanuele,
You might be able to get some inspiration from the aarch64/get-reg-list.c test. The list of MSRs varies with KVM version and host processor, but there may be a set of MSRs that does not vary with host processor and should not be removed in later KVM versions. If that's the case, then the !missing_regs assert concept of aarch64/get-reg-list.c may also apply to this new test. Based on Paolo's comment, I presume at least the !failed_get should apply. Finally, the test should do the E2BIG checks, as Paolo states, but you may also want to create a lib function for KVM_GET_MSR_FEATURE_INDEX_LIST, similar to vcpu_get_reg_list(), if you think it may be of use to other tests.
Thanks, drew
linux-kselftest-mirror@lists.linaro.org
-
Andrew Jones -
Emanuele Giuseppe Esposito -
Paolo Bonzini