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/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
index f12eb01..5e9da2a 100644
--- a/arch/mips/include/asm/kvm_host.h
+++ b/arch/mips/include/asm/kvm_host.h
@@ -56,6 +56,12 @@
#define KVM_REG_MIPS_CP0_CONFIG7 MIPS_CP0_32(16, 7)
#define KVM_REG_MIPS_CP0_XCONTEXT MIPS_CP0_64(20, 0)
#define KVM_REG_MIPS_CP0_ERROREPC MIPS_CP0_64(30, 0)
+#define KVM_REG_MIPS_CP0_KSCRATCH1 MIPS_CP0_64(31, 2)
+#define KVM_REG_MIPS_CP0_KSCRATCH2 MIPS_CP0_64(31, 3)
+#define KVM_REG_MIPS_CP0_KSCRATCH3 MIPS_CP0_64(31, 4)
+#define KVM_REG_MIPS_CP0_KSCRATCH4 MIPS_CP0_64(31, 5)
+#define KVM_REG_MIPS_CP0_KSCRATCH5 MIPS_CP0_64(31, 6)
+#define KVM_REG_MIPS_CP0_KSCRATCH6 MIPS_CP0_64(31, 7)
#define KVM_MAX_VCPUS 1
@@ -376,6 +382,7 @@
u8 fpu_enabled;
u8 msa_enabled;
+ u8 kscratch_enabled;
};
@@ -429,6 +436,18 @@
#define kvm_write_c0_guest_config7(cop0, val) (cop0->reg[MIPS_CP0_CONFIG][7] = (val))
#define kvm_read_c0_guest_errorepc(cop0) (cop0->reg[MIPS_CP0_ERROR_PC][0])
#define kvm_write_c0_guest_errorepc(cop0, val) (cop0->reg[MIPS_CP0_ERROR_PC][0] = (val))
+#define kvm_read_c0_guest_kscratch1(cop0) (cop0->reg[MIPS_CP0_DESAVE][2])
+#define kvm_read_c0_guest_kscratch2(cop0) (cop0->reg[MIPS_CP0_DESAVE][3])
+#define kvm_read_c0_guest_kscratch3(cop0) (cop0->reg[MIPS_CP0_DESAVE][4])
+#define kvm_read_c0_guest_kscratch4(cop0) (cop0->reg[MIPS_CP0_DESAVE][5])
+#define kvm_read_c0_guest_kscratch5(cop0) (cop0->reg[MIPS_CP0_DESAVE][6])
+#define kvm_read_c0_guest_kscratch6(cop0) (cop0->reg[MIPS_CP0_DESAVE][7])
+#define kvm_write_c0_guest_kscratch1(cop0, val) (cop0->reg[MIPS_CP0_DESAVE][2] = (val))
+#define kvm_write_c0_guest_kscratch2(cop0, val) (cop0->reg[MIPS_CP0_DESAVE][3] = (val))
+#define kvm_write_c0_guest_kscratch3(cop0, val) (cop0->reg[MIPS_CP0_DESAVE][4] = (val))
+#define kvm_write_c0_guest_kscratch4(cop0, val) (cop0->reg[MIPS_CP0_DESAVE][5] = (val))
+#define kvm_write_c0_guest_kscratch5(cop0, val) (cop0->reg[MIPS_CP0_DESAVE][6] = (val))
+#define kvm_write_c0_guest_kscratch6(cop0, val) (cop0->reg[MIPS_CP0_DESAVE][7] = (val))
/*
* Some of the guest registers may be modified asynchronously (e.g. from a
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;
}
/**
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);
diff --git a/arch/mips/kvm/trace.h b/arch/mips/kvm/trace.h
index 5d712ec..a38bdab 100644
--- a/arch/mips/kvm/trace.h
+++ b/arch/mips/kvm/trace.h
@@ -178,6 +178,12 @@
{ KVM_TRACE_COP0(16, 7), "Config7" }, \
{ KVM_TRACE_COP0(26, 0), "ECC" }, \
{ KVM_TRACE_COP0(30, 0), "ErrorEPC" }, \
+ { KVM_TRACE_COP0(31, 2), "KScratch1" }, \
+ { KVM_TRACE_COP0(31, 3), "KScratch2" }, \
+ { KVM_TRACE_COP0(31, 4), "KScratch3" }, \
+ { KVM_TRACE_COP0(31, 5), "KScratch4" }, \
+ { KVM_TRACE_COP0(31, 6), "KScratch5" }, \
+ { KVM_TRACE_COP0(31, 7), "KScratch6" }, \
{ KVM_TRACE_HWR( 0, 0), "CPUNum" }, \
{ KVM_TRACE_HWR( 1, 0), "SYNCI_Step" }, \
{ KVM_TRACE_HWR( 2, 0), "CC" }, \
diff --git a/arch/mips/kvm/trap_emul.c b/arch/mips/kvm/trap_emul.c
index b64ca1a..eb191c4 100644
--- a/arch/mips/kvm/trap_emul.c
+++ b/arch/mips/kvm/trap_emul.c
@@ -418,6 +418,8 @@
static int kvm_trap_emul_vcpu_init(struct kvm_vcpu *vcpu)
{
+ vcpu->arch.kscratch_enabled = 0xfc;
+
return 0;
}