| Message ID | 20230121020738.2973-2-kechenl@nvidia.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86: add per-vCPU exits disable capability | expand |
On Sat, Jan 21, 2023 at 02:07:33AM +0000, Kechen Lu wrote: > From: Sean Christopherson <seanjc@google.com> > > Since VMX and SVM both would never update the control bits if exits > are disable after vCPUs are created, only allow setting exits > disable flag before vCPU creation. > > Fixes: 4d5422cea3b6 ("KVM: X86: Provide a capability to disable MWAIT intercepts") > > Signed-off-by: Sean Christopherson <seanjc@google.com> Nit, no blank line between fixes and signed-off-by please. And an RFC on v6? An RFC usually means "I don't think this is correct so do not take it". How can you do that for 6 versions? And know that no one will take an RFC series for that reason (or at least I will not...) thanks, greg k-h
Hi Greg, > -----Original Message----- > From: Greg KH <gregkh@linuxfoundation.org> > Sent: Friday, January 20, 2023 11:28 PM > To: Kechen Lu <kechenl@nvidia.com> > Cc: kvm@vger.kernel.org; seanjc@google.com; pbonzini@redhat.com; > zhi.wang.linux@gmail.com; chao.gao@intel.com; shaoqin.huang@intel.com; > vkuznets@redhat.com; linux-kernel@vger.kernel.org; > stable@vger.kernel.org > Subject: Re: [RFC PATCH v6 1/6] KVM: x86: only allow exits disable before > vCPUs created > > External email: Use caution opening links or attachments > > > On Sat, Jan 21, 2023 at 02:07:33AM +0000, Kechen Lu wrote: > > From: Sean Christopherson <seanjc@google.com> > > > > Since VMX and SVM both would never update the control bits if exits > > are disable after vCPUs are created, only allow setting exits disable > > flag before vCPU creation. > > > > Fixes: 4d5422cea3b6 ("KVM: X86: Provide a capability to disable MWAIT > > intercepts") > > > > Signed-off-by: Sean Christopherson <seanjc@google.com> > > Nit, no blank line between fixes and signed-off-by please. Ack. > > And an RFC on v6? An RFC usually means "I don't think this is correct so do > not take it". How can you do that for 6 versions? And know that no one will > take an RFC series for that reason (or at least I will > not...) Thanks for correcting this, this is my bad. The v2 to v4 revisions, there are big changes on the following patches after this prerequisite patch, so I still "RFC" for the design. But I should drop the "RFC" starting from v5, there are already consensus on the v5 design options Best Regards, Kechen > > thanks, > > greg k-h
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 9807b05a1b57..fb0fcc566d5a 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -7087,6 +7087,7 @@ branch to guests' 0x200 interrupt vector. :Architectures: x86 :Parameters: args[0] defines which exits are disabled :Returns: 0 on success, -EINVAL when args[0] contains invalid exits + or if any vCPU has already been created Valid bits in args[0] are:: diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index da4bbd043a7b..c8ae9c4f9f08 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6227,6 +6227,10 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, if (cap->args[0] & ~KVM_X86_DISABLE_VALID_EXITS) break; + mutex_lock(&kvm->lock); + if (kvm->created_vcpus) + goto disable_exits_unlock; + if ((cap->args[0] & KVM_X86_DISABLE_EXITS_MWAIT) && kvm_can_mwait_in_guest()) kvm->arch.mwait_in_guest = true; @@ -6237,6 +6241,8 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, if (cap->args[0] & KVM_X86_DISABLE_EXITS_CSTATE) kvm->arch.cstate_in_guest = true; r = 0; +disable_exits_unlock: + mutex_unlock(&kvm->lock); break; case KVM_CAP_MSR_PLATFORM_INFO: kvm->arch.guest_can_read_msr_platform_info = cap->args[0];