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kvm: i386: require KVM_CAP_XSAVE

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This was introduced in KVM in Linux 2.6.36, and could already be used at
the time to save/restore FPU data even on older processor.  We can require
it unconditionally and stop using KVM_GET/SET_FPU.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2023-10-17 13:18:15 +02:00
parent f57a4dd311
commit 8bba0a3b76
1 changed files with 2 additions and 68 deletions
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70
target/i386/kvm/kvm.c
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@ -94,6 +94,7 @@ const KVMCapabilityInfo kvm_arch_required_capabilities[] = {
KVM_CAP_INFO(SIGNAL_MSI),
KVM_CAP_INFO(IRQ_ROUTING),
KVM_CAP_INFO(DEBUGREGS),
KVM_CAP_INFO(XSAVE),
KVM_CAP_LAST_INFO
};
@ -137,7 +138,6 @@ static uint32_t has_architectural_pmu_version;
static uint32_t num_architectural_pmu_gp_counters;
static uint32_t num_architectural_pmu_fixed_counters;
static int has_xsave;
static int has_xsave2;
static int has_xcrs;
static int has_pit_state2;
@ -1714,10 +1714,8 @@ static void kvm_init_xsave(CPUX86State *env)
{
if (has_xsave2) {
env->xsave_buf_len = QEMU_ALIGN_UP(has_xsave2, 4096);
} else if (has_xsave) {
env->xsave_buf_len = sizeof(struct kvm_xsave);
} else {
return;
env->xsave_buf_len = sizeof(struct kvm_xsave);
}
env->xsave_buf = qemu_memalign(4096, env->xsave_buf_len);
@ -2592,7 +2590,6 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
return ret;
}
has_xsave = kvm_check_extension(s, KVM_CAP_XSAVE);
has_xcrs = kvm_check_extension(s, KVM_CAP_XCRS);
has_pit_state2 = kvm_check_extension(s, KVM_CAP_PIT_STATE2);
has_sregs2 = kvm_check_extension(s, KVM_CAP_SREGS2) > 0;
@ -2877,40 +2874,11 @@ static int kvm_getput_regs(X86CPU *cpu, int set)
return ret;
}
static int kvm_put_fpu(X86CPU *cpu)
{
CPUX86State *env = &cpu->env;
struct kvm_fpu fpu;
int i;
memset(&fpu, 0, sizeof fpu);
fpu.fsw = env->fpus & ~(7 << 11);
fpu.fsw |= (env->fpstt & 7) << 11;
fpu.fcw = env->fpuc;
fpu.last_opcode = env->fpop;
fpu.last_ip = env->fpip;
fpu.last_dp = env->fpdp;
for (i = 0; i < 8; ++i) {
fpu.ftwx |= (!env->fptags[i]) << i;
}
memcpy(fpu.fpr, env->fpregs, sizeof env->fpregs);
for (i = 0; i < CPU_NB_REGS; i++) {
stq_p(&fpu.xmm[i][0], env->xmm_regs[i].ZMM_Q(0));
stq_p(&fpu.xmm[i][8], env->xmm_regs[i].ZMM_Q(1));
}
fpu.mxcsr = env->mxcsr;
return kvm_vcpu_ioctl(CPU(cpu), KVM_SET_FPU, &fpu);
}
static int kvm_put_xsave(X86CPU *cpu)
{
CPUX86State *env = &cpu->env;
void *xsave = env->xsave_buf;
if (!has_xsave) {
return kvm_put_fpu(cpu);
}
x86_cpu_xsave_all_areas(cpu, xsave, env->xsave_buf_len);
return kvm_vcpu_ioctl(CPU(cpu), KVM_SET_XSAVE, xsave);
@ -3655,46 +3623,12 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
}
static int kvm_get_fpu(X86CPU *cpu)
{
CPUX86State *env = &cpu->env;
struct kvm_fpu fpu;
int i, ret;
ret = kvm_vcpu_ioctl(CPU(cpu), KVM_GET_FPU, &fpu);
if (ret < 0) {
return ret;
}
env->fpstt = (fpu.fsw >> 11) & 7;
env->fpus = fpu.fsw;
env->fpuc = fpu.fcw;
env->fpop = fpu.last_opcode;
env->fpip = fpu.last_ip;
env->fpdp = fpu.last_dp;
for (i = 0; i < 8; ++i) {
env->fptags[i] = !((fpu.ftwx >> i) & 1);
}
memcpy(env->fpregs, fpu.fpr, sizeof env->fpregs);
for (i = 0; i < CPU_NB_REGS; i++) {
env->xmm_regs[i].ZMM_Q(0) = ldq_p(&fpu.xmm[i][0]);
env->xmm_regs[i].ZMM_Q(1) = ldq_p(&fpu.xmm[i][8]);
}
env->mxcsr = fpu.mxcsr;
return 0;
}
static int kvm_get_xsave(X86CPU *cpu)
{
CPUX86State *env = &cpu->env;
void *xsave = env->xsave_buf;
int type, ret;
if (!has_xsave) {
return kvm_get_fpu(cpu);
}
type = has_xsave2 ? KVM_GET_XSAVE2 : KVM_GET_XSAVE;
ret = kvm_vcpu_ioctl(CPU(cpu), type, xsave);
if (ret < 0) {