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authorPaolo Bonzini <pbonzini@redhat.com>2022-04-22 13:30:13 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2022-04-29 19:38:22 +0300
commitd495f942f40aa412f8d4d65951152648cfa09903 (patch)
tree81a4c05ce5fb66d9bdcc613d35f235b5b93e951b /virt
parent86931ff7207bc045fa5439ef97b31859613dc303 (diff)
downloadlinux-d495f942f40aa412f8d4d65951152648cfa09903.tar.xz
KVM: fix bad user ABI for KVM_EXIT_SYSTEM_EVENT
When KVM_EXIT_SYSTEM_EVENT was introduced, it included a flags member that at the time was unused. Unfortunately this extensibility mechanism has several issues: - x86 is not writing the member, so it would not be possible to use it on x86 except for new events - the member is not aligned to 64 bits, so the definition of the uAPI struct is incorrect for 32- on 64-bit userspace. This is a problem for RISC-V, which supports CONFIG_KVM_COMPAT, but fortunately usage of flags was only introduced in 5.18. Since padding has to be introduced, place a new field in there that tells if the flags field is valid. To allow further extensibility, in fact, change flags to an array of 16 values, and store how many of the values are valid. The availability of the new ndata field is tied to a system capability; all architectures are changed to fill in the field. To avoid breaking compilation of userspace that was using the flags field, provide a userspace-only union to overlap flags with data[0]. The new field is placed at the same offset for both 32- and 64-bit userspace. Cc: Will Deacon <will@kernel.org> Cc: Marc Zyngier <maz@kernel.org> Cc: Peter Gonda <pgonda@google.com> Cc: Sean Christopherson <seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reported-by: kernel test robot <lkp@intel.com> Message-Id: <20220422103013.34832-1-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index dfb7dabdbc63..ac57fc2c935f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -4333,6 +4333,7 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
return 0;
#endif
case KVM_CAP_BINARY_STATS_FD:
+ case KVM_CAP_SYSTEM_EVENT_DATA:
return 1;
default:
break;