The patch below does not apply to the 5.16-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 127770ac0d043435375ab86434f31a93efa88215 Mon Sep 17 00:00:00 2001 From: Aaron Lewis aaronlewis@google.com Date: Mon, 14 Feb 2022 21:29:51 +0000 Subject: [PATCH] KVM: x86: Add KVM_CAP_ENABLE_CAP to x86

Follow the precedent set by other architectures that support the VCPU ioctl, KVM_ENABLE_CAP, and advertise the VM extension, KVM_CAP_ENABLE_CAP. This way, userspace can ensure that KVM_ENABLE_CAP is available on a vcpu before using it.

Fixes: 5c919412fe61 ("kvm/x86: Hyper-V synthetic interrupt controller") Signed-off-by: Aaron Lewis aaronlewis@google.com Message-Id: 20220214212950.1776943-1-aaronlewis@google.com Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini pbonzini@redhat.com

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index a4267104db50..3b4da6c7b25f 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -1394,7 +1394,7 @@ documentation when it pops into existence). -------------------

:Capability: KVM_CAP_ENABLE_CAP -:Architectures: mips, ppc, s390 +:Architectures: mips, ppc, s390, x86 :Type: vcpu ioctl :Parameters: struct kvm_enable_cap (in) :Returns: 0 on success; -1 on error diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 641044db415d..b8bd8da32045 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4233,6 +4233,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_EXIT_ON_EMULATION_FAILURE: case KVM_CAP_VCPU_ATTRIBUTES: case KVM_CAP_SYS_ATTRIBUTES: + case KVM_CAP_ENABLE_CAP: r = 1; break; case KVM_CAP_EXIT_HYPERCALL: