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/mips.c b/arch/mips/kvm/mips.c
index 622b9fe..5a2b903 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -9,6 +9,7 @@
* Authors: Sanjay Lal <sanjayl@kymasys.com>
*/
+#include <linux/bitops.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/kdebug.h>
@@ -548,6 +549,15 @@
KVM_REG_MIPS_MSA_CSR,
};
+static u64 kvm_mips_get_one_regs_kscratch[] = {
+ KVM_REG_MIPS_CP0_KSCRATCH1,
+ KVM_REG_MIPS_CP0_KSCRATCH2,
+ KVM_REG_MIPS_CP0_KSCRATCH3,
+ KVM_REG_MIPS_CP0_KSCRATCH4,
+ KVM_REG_MIPS_CP0_KSCRATCH5,
+ KVM_REG_MIPS_CP0_KSCRATCH6,
+};
+
static unsigned long kvm_mips_num_regs(struct kvm_vcpu *vcpu)
{
unsigned long ret;
@@ -561,6 +571,7 @@
}
if (kvm_mips_guest_can_have_msa(&vcpu->arch))
ret += ARRAY_SIZE(kvm_mips_get_one_regs_msa) + 32;
+ ret += __arch_hweight8(vcpu->arch.kscratch_enabled);
ret += kvm_mips_callbacks->num_regs(vcpu);
return ret;
@@ -613,6 +624,16 @@
}
}
+ for (i = 0; i < 6; ++i) {
+ if (!(vcpu->arch.kscratch_enabled & BIT(i + 2)))
+ continue;
+
+ if (copy_to_user(indices, &kvm_mips_get_one_regs_kscratch[i],
+ sizeof(kvm_mips_get_one_regs_kscratch[i])))
+ return -EFAULT;
+ ++indices;
+ }
+
return kvm_mips_callbacks->copy_reg_indices(vcpu, indices);
}
@@ -765,6 +786,31 @@
case KVM_REG_MIPS_CP0_ERROREPC:
v = (long)kvm_read_c0_guest_errorepc(cop0);
break;
+ case KVM_REG_MIPS_CP0_KSCRATCH1 ... KVM_REG_MIPS_CP0_KSCRATCH6:
+ idx = reg->id - KVM_REG_MIPS_CP0_KSCRATCH1 + 2;
+ if (!(vcpu->arch.kscratch_enabled & BIT(idx)))
+ return -EINVAL;
+ switch (idx) {
+ case 2:
+ v = (long)kvm_read_c0_guest_kscratch1(cop0);
+ break;
+ case 3:
+ v = (long)kvm_read_c0_guest_kscratch2(cop0);
+ break;
+ case 4:
+ v = (long)kvm_read_c0_guest_kscratch3(cop0);
+ break;
+ case 5:
+ v = (long)kvm_read_c0_guest_kscratch4(cop0);
+ break;
+ case 6:
+ v = (long)kvm_read_c0_guest_kscratch5(cop0);
+ break;
+ case 7:
+ v = (long)kvm_read_c0_guest_kscratch6(cop0);
+ break;
+ }
+ break;
/* registers to be handled specially */
default:
ret = kvm_mips_callbacks->get_one_reg(vcpu, reg, &v);
@@ -931,6 +977,31 @@
case KVM_REG_MIPS_CP0_ERROREPC:
kvm_write_c0_guest_errorepc(cop0, v);
break;
+ case KVM_REG_MIPS_CP0_KSCRATCH1 ... KVM_REG_MIPS_CP0_KSCRATCH6:
+ idx = reg->id - KVM_REG_MIPS_CP0_KSCRATCH1 + 2;
+ if (!(vcpu->arch.kscratch_enabled & BIT(idx)))
+ return -EINVAL;
+ switch (idx) {
+ case 2:
+ kvm_write_c0_guest_kscratch1(cop0, v);
+ break;
+ case 3:
+ kvm_write_c0_guest_kscratch2(cop0, v);
+ break;
+ case 4:
+ kvm_write_c0_guest_kscratch3(cop0, v);
+ break;
+ case 5:
+ kvm_write_c0_guest_kscratch4(cop0, v);
+ break;
+ case 6:
+ kvm_write_c0_guest_kscratch5(cop0, v);
+ break;
+ case 7:
+ kvm_write_c0_guest_kscratch6(cop0, v);
+ break;
+ }
+ break;
/* registers to be handled specially */
default:
return kvm_mips_callbacks->set_one_reg(vcpu, reg, v);