Commit fabacc0f authored by Jan Kiszka's avatar Jan Kiszka Committed by Marcelo Tosatti
Browse files

kvm: x86: Avoid runtime allocation of xsave buffer 



Keep a per-VCPU xsave buffer for kvm_put/get_xsave instead of
continuously allocating and freeing it on state sync.

Signed-off-by: default avatarJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 6b42494b

target-i386/cpu.h

+2 −1
Original line number Diff line number Diff line
@@ -751,6 +751,7 @@ typedef struct CPUX86State { 
    uint32_t cpuid_svm_features;

    bool tsc_valid;

    int tsc_khz;

    void *kvm_xsave_buf;



    /* in order to simplify APIC support, we leave this pointer to the

       user */

target-i386/kvm.c

+7 −8
Original line number Diff line number Diff line
@@ -516,6 +516,10 @@ int kvm_arch_init_vcpu(CPUState *env) 
        }

    }



    if (kvm_has_xsave()) {

        env->kvm_xsave_buf = qemu_memalign(4096, sizeof(struct kvm_xsave));

    }



    return 0;

}
@@ -771,15 +775,14 @@ static int kvm_put_fpu(CPUState *env) 


static int kvm_put_xsave(CPUState *env)

{

    int i, r;

    struct kvm_xsave* xsave;

    struct kvm_xsave* xsave = env->kvm_xsave_buf;

    uint16_t cwd, swd, twd;

    int i, r;



    if (!kvm_has_xsave()) {

        return kvm_put_fpu(env);

    }



    xsave = qemu_memalign(4096, sizeof(struct kvm_xsave));

    memset(xsave, 0, sizeof(struct kvm_xsave));

    twd = 0;

    swd = env->fpus & ~(7 << 11);
@@ -801,7 +804,6 @@ static int kvm_put_xsave(CPUState *env) 
    memcpy(&xsave->region[XSAVE_YMMH_SPACE], env->ymmh_regs,

            sizeof env->ymmh_regs);

    r = kvm_vcpu_ioctl(env, KVM_SET_XSAVE, xsave);

    g_free(xsave);

    return r;

}
@@ -978,7 +980,7 @@ static int kvm_get_fpu(CPUState *env) 


static int kvm_get_xsave(CPUState *env)

{

    struct kvm_xsave* xsave;

    struct kvm_xsave* xsave = env->kvm_xsave_buf;

    int ret, i;

    uint16_t cwd, swd, twd;
@@ -986,10 +988,8 @@ static int kvm_get_xsave(CPUState *env) 
        return kvm_get_fpu(env);

    }



    xsave = qemu_memalign(4096, sizeof(struct kvm_xsave));

    ret = kvm_vcpu_ioctl(env, KVM_GET_XSAVE, xsave);

    if (ret < 0) {

        g_free(xsave);

        return ret;

    }
@@ -1013,7 +1013,6 @@ static int kvm_get_xsave(CPUState *env) 
    env->xstate_bv = *(uint64_t *)&xsave->region[XSAVE_XSTATE_BV];

    memcpy(env->ymmh_regs, &xsave->region[XSAVE_YMMH_SPACE],

            sizeof env->ymmh_regs);

    g_free(xsave);

    return 0;

}