diff options
| author | David Woodhouse <dwmw@amazon.co.uk> | 2022-11-27 12:22:10 +0000 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-11-30 10:59:37 -0500 |
| commit | d8ba8ba4c801b794f47852a6f1821ea48f83b5d1 (patch) | |
| tree | cf8743dc182b1ca2b49a8c619e834b4748b2639e /tools | |
| parent | 5ec3289b31ab9bb209be59cee360aac4b03f320a (diff) | |
KVM: x86/xen: Allow XEN_RUNSTATE_UPDATE flag behaviour to be configured
Closer inspection of the Xen code shows that we aren't supposed to be
using the XEN_RUNSTATE_UPDATE flag unconditionally. It should be
explicitly enabled by guests through the HYPERVISOR_vm_assist hypercall.
If we randomly set the top bit of ->state_entry_time for a guest that
hasn't asked for it and doesn't expect it, that could make the runtimes
fail to add up and confuse the guest. Without the flag it's perfectly
safe for a vCPU to read its own vcpu_runstate_info; just not for one
vCPU to read *another's*.
I briefly pondered adding a word for the whole set of VMASST_TYPE_*
flags but the only one we care about for HVM guests is this, so it
seemed a bit pointless.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20221127122210.248427-3-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c index 7f39815f1772..c9b0110d73f3 100644 --- a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c +++ b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c @@ -440,6 +440,7 @@ int main(int argc, char *argv[]) TEST_REQUIRE(xen_caps & KVM_XEN_HVM_CONFIG_SHARED_INFO); bool do_runstate_tests = !!(xen_caps & KVM_XEN_HVM_CONFIG_RUNSTATE); + bool do_runstate_flag = !!(xen_caps & KVM_XEN_HVM_CONFIG_RUNSTATE_UPDATE_FLAG); bool do_eventfd_tests = !!(xen_caps & KVM_XEN_HVM_CONFIG_EVTCHN_2LEVEL); bool do_evtchn_tests = do_eventfd_tests && !!(xen_caps & KVM_XEN_HVM_CONFIG_EVTCHN_SEND); @@ -475,6 +476,19 @@ int main(int argc, char *argv[]) }; vm_ioctl(vm, KVM_XEN_HVM_SET_ATTR, &lm); + if (do_runstate_flag) { + struct kvm_xen_hvm_attr ruf = { + .type = KVM_XEN_ATTR_TYPE_RUNSTATE_UPDATE_FLAG, + .u.runstate_update_flag = 1, + }; + vm_ioctl(vm, KVM_XEN_HVM_SET_ATTR, &ruf); + + ruf.u.runstate_update_flag = 0; + vm_ioctl(vm, KVM_XEN_HVM_GET_ATTR, &ruf); + TEST_ASSERT(ruf.u.runstate_update_flag == 1, + "Failed to read back RUNSTATE_UPDATE_FLAG attr"); + } + struct kvm_xen_hvm_attr ha = { .type = KVM_XEN_ATTR_TYPE_SHARED_INFO, .u.shared_info.gfn = SHINFO_REGION_GPA / PAGE_SIZE, |