MIPS: KVM: Add KScratch registers
Allow up to 6 KVM guest KScratch registers to be enabled and accessed
via the KVM guest register API and from the guest itself (the fallback
reading and writing of commpage registers is sufficient for KScratch
registers to work as expected).
User mode can expose the registers by setting the appropriate bits of
the guest Config4.KScrExist field. KScratch registers that aren't usable
won't be writeable via the KVM Ioctl API.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c
index 4ca5450..5f0354c 100644
--- a/arch/mips/kvm/emulate.c
+++ b/arch/mips/kvm/emulate.c
@@ -941,7 +941,12 @@
unsigned int kvm_mips_config4_wrmask(struct kvm_vcpu *vcpu)
{
/* Config5 is optional */
- return MIPS_CONF_M;
+ unsigned int mask = MIPS_CONF_M;
+
+ /* KScrExist */
+ mask |= (unsigned int)vcpu->arch.kscratch_enabled << 16;
+
+ return mask;
}
/**