MIPS: KVM: Wire up FPU capability

Now that the code is in place for KVM to support FPU in MIPS KVM guests,
wire up the new KVM_CAP_MIPS_FPU capability.

For backwards compatibility, the capability must be explicitly enabled
in order to detect or make use of the FPU from the guest.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-api@vger.kernel.org
Cc: linux-doc@vger.kernel.org

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index f3c1983607856763db92d0439ebcb50ba66c4d04..a1e9bfa5fe9eaeca1f4c77cdbdfd6d9985526514 100644 (file)
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3312,6 +3312,19 @@ Parameters: none
 This capability enables the in-kernel irqchip for s390. Please refer to
 "4.24 KVM_CREATE_IRQCHIP" for details.
 
+6.9 KVM_CAP_MIPS_FPU
+
+Architectures: mips
+Target: vcpu
+Parameters: args[0] is reserved for future use (should be 0).
+
+This capability allows the use of the host Floating Point Unit by the guest. It
+allows the Config1.FP bit to be set to enable the FPU in the guest. Once this is
+done the KVM_REG_MIPS_FPR_* and KVM_REG_MIPS_FCR_* registers can be accessed
+(depending on the current guest FPU register mode), and the Status.FR,
+Config5.FRE bits are accessible via the KVM API and also from the guest,
+depending on them being supported by the FPU.
+
 7. Capabilities that can be enabled on VMs
 ------------------------------------------
 

diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 5e41afe15ae8acbb8d2d09dc7f6765889b806eb3..7f86cb73d05d740d07ecac4bed3a99b7d71b783b 100644 (file)
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -797,6 +797,30 @@ static int kvm_mips_set_reg(struct kvm_vcpu *vcpu,
        return 0;
 }
 
+static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
+                                    struct kvm_enable_cap *cap)
+{
+       int r = 0;
+
+       if (!kvm_vm_ioctl_check_extension(vcpu->kvm, cap->cap))
+               return -EINVAL;
+       if (cap->flags)
+               return -EINVAL;
+       if (cap->args[0])
+               return -EINVAL;
+
+       switch (cap->cap) {
+       case KVM_CAP_MIPS_FPU:
+               vcpu->arch.fpu_enabled = true;
+               break;
+       default:
+               r = -EINVAL;
+               break;
+       }
+
+       return r;
+}
+
 long kvm_arch_vcpu_ioctl(struct file *filp, unsigned int ioctl,
                         unsigned long arg)
 {
@@ -854,6 +878,15 @@ long kvm_arch_vcpu_ioctl(struct file *filp, unsigned int ioctl,
                        r = kvm_vcpu_ioctl_interrupt(vcpu, &irq);
                        break;
                }
+       case KVM_ENABLE_CAP: {
+               struct kvm_enable_cap cap;
+
+               r = -EFAULT;
+               if (copy_from_user(&cap, argp, sizeof(cap)))
+                       goto out;
+               r = kvm_vcpu_ioctl_enable_cap(vcpu, &cap);
+               break;
+       }
        default:
                r = -ENOIOCTLCMD;
        }
@@ -962,11 +995,15 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 
        switch (ext) {
        case KVM_CAP_ONE_REG:
+       case KVM_CAP_ENABLE_CAP:
                r = 1;
                break;
        case KVM_CAP_COALESCED_MMIO:
                r = KVM_COALESCED_MMIO_PAGE_OFFSET;
                break;
+       case KVM_CAP_MIPS_FPU:
+               r = !!cpu_has_fpu;
+               break;
        default:
                r = 0;
                break;

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 1162ef7a3fa1394296beae511a2221ee9dc10d5f..ce49688976d2ced343f3fe149be682ae3d747c5c 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -802,6 +802,7 @@ struct kvm_ppc_smmu_info {
 #define KVM_CAP_S390_MEM_OP 108
 #define KVM_CAP_S390_USER_STSI 109
 #define KVM_CAP_S390_SKEYS 110
+#define KVM_CAP_MIPS_FPU 111
 
 #ifdef KVM_CAP_IRQ_ROUTING