[PATCH v5 7/7] mips/kvm: Support MSA in MIPS KVM guests

James Hogan
2016-02-03T17:17:18Z

Support the new KVM_CAP_MIPS_MSA capability, which allows MIPS SIMD
Architecture (MSA) to be exposed to the KVM guest.

The capability is enabled if the guest core has MSA according to its
Config3 register. Various config bits are now writeable so that KVM is
aware of the configuration (Config3.MSAP) and so that QEMU can
save/restore the guest modifiable bits (Config5.MSAEn). The MSACSR/MSAIR
registers and the MSA vector registers are now saved/restored. Since the
FP registers are a subset of the vector registers, they are omitted if
the guest has MSA.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Leon Alrae <leon.alrae@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
---
Changes in v5:
- Restore MSA FP state using restore_msa_fp_status(env) (Leon).

Changes in v2:
- Change (1 << x) to (1U << x) in important places to avoid compiler
undefined behaviour (Leon).
- Removed update of linux-headers/linux/kvm.h (Paolo).
---
target-mips/kvm.c | 129 +++++++++++++++++++++++++++++++++++++++++++++---------
1 file changed, 109 insertions(+), 20 deletions(-)

diff --git a/target-mips/kvm.c b/target-mips/kvm.c
index a1f5b6012edd..950bc05b7c32 100644
--- a/target-mips/kvm.c
+++ b/target-mips/kvm.c
@@ -31,6 +31,7 @@
do { if (DEBUG_KVM) { fprintf(stderr, fmt, ## __VA_ARGS__); } } while (0)

static int kvm_mips_fpu_cap;
+static int kvm_mips_msa_cap;

const KVMCapabilityInfo kvm_arch_required_capabilities[] = {
KVM_CAP_LAST_INFO
@@ -49,6 +50,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
kvm_set_sigmask_len(s, 16);

kvm_mips_fpu_cap = kvm_check_extension(s, KVM_CAP_MIPS_FPU);
+ kvm_mips_msa_cap = kvm_check_extension(s, KVM_CAP_MIPS_MSA);

DPRINTF("%s\n", __func__);
return 0;
@@ -71,6 +73,15 @@ int kvm_arch_init_vcpu(CPUState *cs)
}
}

+ if (kvm_mips_msa_cap && env->CP0_Config3 & (1 << CP0C3_MSAP)) {
+ ret = kvm_vcpu_enable_cap(cs, KVM_CAP_MIPS_MSA, 0, 0);
+ if (ret < 0) {
+ /* mark unsupported so it gets disabled on reset */
+ kvm_mips_msa_cap = 0;
+ ret = 0;
+ }
+ }
+
DPRINTF("%s\n", __func__);
return ret;
}
@@ -83,6 +94,10 @@ void kvm_mips_reset_vcpu(MIPSCPU *cpu)
fprintf(stderr, "Warning: KVM does not support FPU, disabling\n");
env->CP0_Config1 &= ~(1 << CP0C1_FP);
}
+ if (!kvm_mips_msa_cap && env->CP0_Config3 & (1 << CP0C3_MSAP)) {
+ fprintf(stderr, "Warning: KVM does not support MSA, disabling\n");
+ env->CP0_Config3 &= ~(1 << CP0C3_MSAP);
+ }

DPRINTF("%s\n", __func__);
}
@@ -373,9 +388,11 @@ static inline int kvm_mips_get_one_ureg64(CPUState *cs, uint64_t reg_id,
#define KVM_REG_MIPS_CP0_CONFIG1_MASK ((1U << CP0C1_M) | \
(1U << CP0C1_FP))
#define KVM_REG_MIPS_CP0_CONFIG2_MASK (1U << CP0C2_M)
-#define KVM_REG_MIPS_CP0_CONFIG3_MASK (1U << CP0C3_M)
+#define KVM_REG_MIPS_CP0_CONFIG3_MASK ((1U << CP0C3_M) | \
+ (1U << CP0C3_MSAP))
#define KVM_REG_MIPS_CP0_CONFIG4_MASK (1U << CP0C4_M)
-#define KVM_REG_MIPS_CP0_CONFIG5_MASK ((1U << CP0C5_UFE) | \
+#define KVM_REG_MIPS_CP0_CONFIG5_MASK ((1U << CP0C5_MSAEn) | \
+ (1U << CP0C5_UFE) | \
(1U << CP0C5_FRE) | \
(1U << CP0C5_UFR))

@@ -564,17 +581,53 @@ static int kvm_mips_put_fpu_registers(CPUState *cs, int level)
ret = err;
}

- /* Floating point registers */
+ /*
+ * FPU register state is a subset of MSA vector state, so don't put FPU
+ * registers if we're emulating a CPU with MSA.
+ */
+ if (!(env->CP0_Config3 & (1 << CP0C3_MSAP))) {
+ /* Floating point registers */
+ for (i = 0; i < 32; ++i) {
+ if (env->CP0_Status & (1 << CP0St_FR)) {
+ err = kvm_mips_put_one_ureg64(cs, KVM_REG_MIPS_FPR_64(i),
+ &env->active_fpu.fpr[i].d);
+ } else {
+ err = kvm_mips_get_one_ureg(cs, KVM_REG_MIPS_FPR_32(i),
+ &env->active_fpu.fpr[i].w[FP_ENDIAN_IDX]);
+ }
+ if (err < 0) {
+ DPRINTF("%s: Failed to put FPR%u (%d)\n", __func__, i, err);
+ ret = err;
+ }
+ }
+ }
+ }
+
+ /* Only put MSA state if we're emulating a CPU with MSA */
+ if (env->CP0_Config3 & (1 << CP0C3_MSAP)) {
+ /* MSA Control Registers */
+ if (level == KVM_PUT_FULL_STATE) {
+ err = kvm_mips_put_one_reg(cs, KVM_REG_MIPS_MSA_IR,
+ &env->msair);
+ if (err < 0) {
+ DPRINTF("%s: Failed to put MSA_IR (%d)\n", __func__, err);
+ ret = err;
+ }
+ }
+ err = kvm_mips_put_one_reg(cs, KVM_REG_MIPS_MSA_CSR,
+ &env->active_tc.msacsr);
+ if (err < 0) {
+ DPRINTF("%s: Failed to put MSA_CSR (%d)\n", __func__, err);
+ ret = err;
+ }
+
+ /* Vector registers (includes FP registers) */
for (i = 0; i < 32; ++i) {
- if (env->CP0_Status & (1 << CP0St_FR)) {
- err = kvm_mips_put_one_ureg64(cs, KVM_REG_MIPS_FPR_64(i),
- &env->active_fpu.fpr[i].d);
- } else {
- err = kvm_mips_get_one_ureg(cs, KVM_REG_MIPS_FPR_32(i),
- &env->active_fpu.fpr[i].w[FP_ENDIAN_IDX]);
- }
+ /* Big endian MSA not supported by QEMU yet anyway */
+ err = kvm_mips_put_one_reg64(cs, KVM_REG_MIPS_VEC_128(i),
+ env->active_fpu.fpr[i].wr.d);
if (err < 0) {
- DPRINTF("%s: Failed to put FPR%u (%d)\n", __func__, i, err);
+ DPRINTF("%s: Failed to put VEC%u (%d)\n", __func__, i, err);
ret = err;
}
}
@@ -608,17 +661,53 @@ static int kvm_mips_get_fpu_registers(CPUState *cs)
restore_fp_status(env);
}

- /* Floating point registers */
- for (i = 0; i < 32; ++i) {
- if (env->CP0_Status & (1 << CP0St_FR)) {
- err = kvm_mips_get_one_ureg64(cs, KVM_REG_MIPS_FPR_64(i),
- &env->active_fpu.fpr[i].d);
- } else {
- err = kvm_mips_get_one_ureg(cs, KVM_REG_MIPS_FPR_32(i),
- &env->active_fpu.fpr[i].w[FP_ENDIAN_IDX]);
+ /*
+ * FPU register state is a subset of MSA vector state, so don't save FPU
+ * registers if we're emulating a CPU with MSA.
+ */
+ if (!(env->CP0_Config3 & (1 << CP0C3_MSAP))) {
+ /* Floating point registers */
+ for (i = 0; i < 32; ++i) {
+ if (env->CP0_Status & (1 << CP0St_FR)) {
+ err = kvm_mips_get_one_ureg64(cs, KVM_REG_MIPS_FPR_64(i),
+ &env->active_fpu.fpr[i].d);
+ } else {
+ err = kvm_mips_get_one_ureg(cs, KVM_REG_MIPS_FPR_32(i),
+ &env->active_fpu.fpr[i].w[FP_ENDIAN_IDX]);
+ }
+ if (err < 0) {
+ DPRINTF("%s: Failed to get FPR%u (%d)\n", __func__, i, err);
+ ret = err;
+ }
}
+ }
+ }
+
+ /* Only get MSA state if we're emulating a CPU with MSA */
+ if (env->CP0_Config3 & (1 << CP0C3_MSAP)) {
+ /* MSA Control Registers */
+ err = kvm_mips_get_one_reg(cs, KVM_REG_MIPS_MSA_IR,
+ &env->msair);
+ if (err < 0) {
+ DPRINTF("%s: Failed to get MSA_IR (%d)\n", __func__, err);
+ ret = err;
+ }
+ err = kvm_mips_get_one_reg(cs, KVM_REG_MIPS_MSA_CSR,
+ &env->active_tc.msacsr);
+ if (err < 0) {
+ DPRINTF("%s: Failed to get MSA_CSR (%d)\n", __func__, err);
+ ret = err;
+ } else {
+ restore_msa_fp_status(env);
+ }
+
+ /* Vector registers (includes FP registers) */
+ for (i = 0; i < 32; ++i) {
+ /* Big endian MSA not supported by QEMU yet anyway */
+ err = kvm_mips_get_one_reg64(cs, KVM_REG_MIPS_VEC_128(i),
+ env->active_fpu.fpr[i].wr.d);
if (err < 0) {
- DPRINTF("%s: Failed to get FPR%u (%d)\n", __func__, i, err);
+ DPRINTF("%s: Failed to get VEC%u (%d)\n", __func__, i, err);
ret = err;
}
}
--
2.4.10