[Qemu-devel] [PATCH v3 11/15] target/arm/kvm64: Add kvm_arch_get/put_sve

[Andrew Jones <drjones@redhat.com>]

These are the SVE equivalents to kvm_arch_get/put_fpsimd. Note, the
swabbing is different than it is for fpsmid because the vector format
is a little-endian stream of words.

Signed-off-by: Andrew Jones <drjones@redhat.com>
---
 target/arm/kvm64.c | 150 +++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 146 insertions(+), 4 deletions(-)

diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c
index 0b004d5d3050..f5c99984f25f 100644
--- a/target/arm/kvm64.c
+++ b/target/arm/kvm64.c
@@ -671,11 +671,12 @@ int kvm_arch_destroy_vcpu(CPUState *cs)
 bool kvm_arm_reg_syncs_via_cpreg_list(uint64_t regidx)
 {
     /* Return true if the regidx is a register we should synchronize
-     * via the cpreg_tuples array (ie is not a core reg we sync by
-     * hand in kvm_arch_get/put_registers())
+     * via the cpreg_tuples array (ie is not a core or sve reg that
+     * we sync by hand in kvm_arch_get/put_registers())
      */
     switch (regidx & KVM_REG_ARM_COPROC_MASK) {
     case KVM_REG_ARM_CORE:
+    case KVM_REG_ARM64_SVE:
         return false;
     default:
         return true;
@@ -761,6 +762,85 @@ static int kvm_arch_put_fpsimd(CPUState *cs)
     return 0;
 }
 
+/*
+ * SVE registers are encoded in KVM's memory in an endianness-invariant format.
+ * The byte at offset i from the start of the in-memory representation contains
+ * the bits [(7 + 8 * i) : (8 * i)] of the register value. As this means the
+ * lowest offsets are stored in the lowest memory addresses, then that nearly
+ * matches QEMU's representation, which is to use an array of host-endian
+ * uint64_t's, where the lower offsets are at the lower indices. To complete
+ * the translation we just need to byte swap the uint64_t's on big-endian hosts.
+ */
+#ifdef HOST_WORDS_BIGENDIAN
+static uint64_t *sve_bswap64(uint64_t *dst, uint64_t *src, int nr)
+{
+    int i;
+
+    for (i = 0; i < nr; ++i) {
+        dst[i] = bswap64(src[i]);
+    }
+
+    return dst;
+}
+#endif
+
+/*
+ * KVM SVE registers come in slices where ZREGs have a slice size of 2048 bits
+ * and PREGS and the FFR have a slice size of 256 bits. However we simply hard
+ * code the slice index to zero for now as it's unlikely we'll need more than
+ * one slice for quite some time.
+ */
+static int kvm_arch_put_sve(CPUState *cs)
+{
+    ARMCPU *cpu = ARM_CPU(cs);
+    CPUARMState *env = &cpu->env;
+#ifdef HOST_WORDS_BIGENDIAN
+    uint64_t tmp[ARM_MAX_VQ * 2];
+#endif
+    uint64_t *r;
+    struct kvm_one_reg reg;
+    int n, ret;
+
+    for (n = 0; n < KVM_ARM64_SVE_NUM_ZREGS; ++n) {
+        r = &env->vfp.zregs[n].d[0];
+#ifdef HOST_WORDS_BIGENDIAN
+        r = sve_bswap64(tmp, r, cpu->sve_max_vq * 2);
+#endif
+        reg.addr = (uintptr_t)r;
+        reg.id = KVM_REG_ARM64_SVE_ZREG(n, 0);
+        ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &reg);
+        if (ret) {
+            return ret;
+        }
+    }
+
+    for (n = 0; n < KVM_ARM64_SVE_NUM_PREGS; ++n) {
+        r = &env->vfp.pregs[n].p[0];
+#ifdef HOST_WORDS_BIGENDIAN
+        r = sve_bswap64(tmp, r, DIV_ROUND_UP(cpu->sve_max_vq, 8));
+#endif
+        reg.addr = (uintptr_t)r;
+        reg.id = KVM_REG_ARM64_SVE_PREG(n, 0);
+        ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &reg);
+        if (ret) {
+            return ret;
+        }
+    }
+
+    r = &env->vfp.pregs[FFR_PRED_NUM].p[0];
+#ifdef HOST_WORDS_BIGENDIAN
+    r = sve_bswap64(tmp, r, DIV_ROUND_UP(cpu->sve_max_vq, 8));
+#endif
+    reg.addr = (uintptr_t)r;
+    reg.id = KVM_REG_ARM64_SVE_FFR(0);
+    ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &reg);
+    if (ret) {
+        return ret;
+    }
+
+    return 0;
+}
+
 int kvm_arch_put_registers(CPUState *cs, int level)
 {
     struct kvm_one_reg reg;
@@ -855,7 +935,11 @@ int kvm_arch_put_registers(CPUState *cs, int level)
         }
     }
 
-    ret = kvm_arch_put_fpsimd(cs);
+    if (cpu_isar_feature(aa64_sve, cpu)) {
+        ret = kvm_arch_put_sve(cs);
+    } else {
+        ret = kvm_arch_put_fpsimd(cs);
+    }
     if (ret) {
         return ret;
     }
@@ -918,6 +1002,60 @@ static int kvm_arch_get_fpsimd(CPUState *cs)
     return 0;
 }
 
+/*
+ * KVM SVE registers come in slices where ZREGs have a slice size of 2048 bits
+ * and PREGS and the FFR have a slice size of 256 bits. However we simply hard
+ * code the slice index to zero for now as it's unlikely we'll need more than
+ * one slice for quite some time.
+ */
+static int kvm_arch_get_sve(CPUState *cs)
+{
+    ARMCPU *cpu = ARM_CPU(cs);
+    CPUARMState *env = &cpu->env;
+    struct kvm_one_reg reg;
+    uint64_t *r;
+    int n, ret;
+
+    for (n = 0; n < KVM_ARM64_SVE_NUM_ZREGS; ++n) {
+        r = &env->vfp.zregs[n].d[0];
+        reg.addr = (uintptr_t)r;
+        reg.id = KVM_REG_ARM64_SVE_ZREG(n, 0);
+        ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, &reg);
+        if (ret) {
+            return ret;
+        }
+#ifdef HOST_WORDS_BIGENDIAN
+        sve_bswap64(r, r, cpu->sve_max_vq * 2);
+#endif
+    }
+
+    for (n = 0; n < KVM_ARM64_SVE_NUM_PREGS; ++n) {
+        r = &env->vfp.pregs[n].p[0];
+        reg.addr = (uintptr_t)r;
+        reg.id = KVM_REG_ARM64_SVE_PREG(n, 0);
+        ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, &reg);
+        if (ret) {
+            return ret;
+        }
+#ifdef HOST_WORDS_BIGENDIAN
+        sve_bswap64(r, r, DIV_ROUND_UP(cpu->sve_max_vq, 8));
+#endif
+    }
+
+    r = &env->vfp.pregs[FFR_PRED_NUM].p[0];
+    reg.addr = (uintptr_t)r;
+    reg.id = KVM_REG_ARM64_SVE_FFR(0);
+    ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, &reg);
+    if (ret) {
+        return ret;
+    }
+#ifdef HOST_WORDS_BIGENDIAN
+    sve_bswap64(r, r, DIV_ROUND_UP(cpu->sve_max_vq, 8));
+#endif
+
+    return 0;
+}
+
 int kvm_arch_get_registers(CPUState *cs)
 {
     struct kvm_one_reg reg;
@@ -1012,7 +1150,11 @@ int kvm_arch_get_registers(CPUState *cs)
         env->spsr = env->banked_spsr[i];
     }
 
-    ret = kvm_arch_get_fpsimd(cs);
+    if (cpu_isar_feature(aa64_sve, cpu)) {
+        ret = kvm_arch_get_sve(cs);
+    } else {
+        ret = kvm_arch_get_fpsimd(cs);
+    }
     if (ret) {
         return ret;
     }
-- 
2.20.1