Re: [PATCH 4/4] qemu-kvm: Enable XSAVE live migration support

[Jan Kiszka <jan.kiszka@web.de>]

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Sheng Yang wrote:
> Based on upstream xsave related fields.
> 
> Signed-off-by: Sheng Yang <sheng@linux.intel.com>
> ---
>  qemu-kvm-x86.c |   95 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  qemu-kvm.c     |   24 ++++++++++++++
>  qemu-kvm.h     |   28 ++++++++++++++++
>  3 files changed, 146 insertions(+), 1 deletions(-)
> 
> diff --git a/qemu-kvm-x86.c b/qemu-kvm-x86.c
> index 3c33e64..dcef8b5 100644
> --- a/qemu-kvm-x86.c
> +++ b/qemu-kvm-x86.c
> @@ -772,10 +772,26 @@ static void get_seg(SegmentCache *lhs, const struct kvm_segment *rhs)
>  	| (rhs->avl * DESC_AVL_MASK);
>  }
>  
> +#ifdef KVM_CAP_XSAVE
> +#define XSAVE_CWD_RIP     2
> +#define XSAVE_CWD_RDP     4
> +#define XSAVE_MXCSR       6
> +#define XSAVE_ST_SPACE    8
> +#define XSAVE_XMM_SPACE   40
> +#define XSAVE_XSTATE_BV   128
> +#define XSAVE_YMMH_SPACE  144
> +#endif
> +
>  void kvm_arch_load_regs(CPUState *env, int level)
>  {
>      struct kvm_regs regs;
>      struct kvm_fpu fpu;
> +#ifdef KVM_CAP_XSAVE
> +    struct kvm_xsave* xsave;
> +#endif
> +#ifdef KVM_CAP_XCRS
> +    struct kvm_xcrs xcrs;
> +#endif
>      struct kvm_sregs sregs;
>      struct kvm_msr_entry msrs[100];
>      int rc, n, i;
> @@ -806,16 +822,53 @@ void kvm_arch_load_regs(CPUState *env, int level)
>  
>      kvm_set_regs(env, &regs);
>  
> +#ifdef KVM_CAP_XSAVE
> +    if (kvm_check_extension(kvm_state, KVM_CAP_XSAVE)) {
> +        uint16_t cwd, swd, twd, fop;
> +
> +        xsave = qemu_memalign(4096, sizeof(struct kvm_xsave));
> +        memset(xsave, 0, sizeof(struct kvm_xsave));
> +        cwd = swd = twd = fop = 0;
> +        swd = env->fpus & ~(7 << 11);
> +        swd |= (env->fpstt & 7) << 11;
> +        cwd = env->fpuc;
> +        for (i = 0; i < 8; ++i)
> +            twd |= (!env->fptags[i]) << i;
> +        xsave->region[0] = (uint32_t)(swd << 16) + cwd;
> +        xsave->region[1] = (uint32_t)(fop << 16) + twd;
> +        memcpy(&xsave->region[XSAVE_ST_SPACE], env->fpregs,
> +                sizeof env->fpregs);
> +        memcpy(&xsave->region[XSAVE_XMM_SPACE], env->xmm_regs,
> +                sizeof env->xmm_regs);
> +        xsave->region[XSAVE_MXCSR] = env->mxcsr;
> +        *(uint64_t *)&xsave->region[XSAVE_XSTATE_BV] = env->xstate_bv;
> +        memcpy(&xsave->region[XSAVE_YMMH_SPACE], env->ymmh_regs,
> +                sizeof env->ymmh_regs);
> +        kvm_set_xsave(env, xsave);
> +#ifdef KVM_CAP_XCRS
> +        if (kvm_check_extension(kvm_state, KVM_CAP_XCRS)) {
> +            xcrs.nr_xcrs = 1;
> +            xcrs.flags = 0;
> +            xcrs.xcrs[0].xcr = 0;
> +            xcrs.xcrs[0].value = env->xcr0;
> +            kvm_set_xcrs(env, &xcrs);
> +        }
> +#endif /* KVM_CAP_XCRS */
> +    } else {
> +#endif /* KVM_CAP_XSAVE */

Why not reusing kvm_put/get_xsave as defined for upstream? There should
be enough examples for that pattern. The result will be a tiny qemu-kvm
patch.

Jan

>      memset(&fpu, 0, sizeof fpu);
>      fpu.fsw = env->fpus & ~(7 << 11);
>      fpu.fsw |= (env->fpstt & 7) << 11;
>      fpu.fcw = env->fpuc;
>      for (i = 0; i < 8; ++i)
> -	fpu.ftwx |= (!env->fptags[i]) << i;
> +        fpu.ftwx |= (!env->fptags[i]) << i;
>      memcpy(fpu.fpr, env->fpregs, sizeof env->fpregs);
>      memcpy(fpu.xmm, env->xmm_regs, sizeof env->xmm_regs);
>      fpu.mxcsr = env->mxcsr;
>      kvm_set_fpu(env, &fpu);
> +#ifdef KVM_CAP_XSAVE
> +    }
> +#endif
>  
>      memset(sregs.interrupt_bitmap, 0, sizeof(sregs.interrupt_bitmap));
>      if (env->interrupt_injected >= 0) {
> @@ -934,6 +987,12 @@ void kvm_arch_save_regs(CPUState *env)
>  {
>      struct kvm_regs regs;
>      struct kvm_fpu fpu;
> +#ifdef KVM_CAP_XSAVE
> +    struct kvm_xsave* xsave;
> +#endif
> +#ifdef KVM_CAP_XCRS
> +    struct kvm_xcrs xcrs;
> +#endif
>      struct kvm_sregs sregs;
>      struct kvm_msr_entry msrs[100];
>      uint32_t hflags;
> @@ -965,6 +1024,37 @@ void kvm_arch_save_regs(CPUState *env)
>      env->eflags = regs.rflags;
>      env->eip = regs.rip;
>  
> +#ifdef KVM_CAP_XSAVE
> +    if (kvm_check_extension(kvm_state, KVM_CAP_XSAVE)) {
> +        uint16_t cwd, swd, twd, fop;
> +        xsave = qemu_memalign(4096, sizeof(struct kvm_xsave));
> +        kvm_get_xsave(env, xsave);
> +        cwd = (uint16_t)xsave->region[0];
> +        swd = (uint16_t)(xsave->region[0] >> 16);
> +        twd = (uint16_t)xsave->region[1];
> +        fop = (uint16_t)(xsave->region[1] >> 16);
> +        env->fpstt = (swd >> 11) & 7;
> +        env->fpus = swd;
> +        env->fpuc = cwd;
> +        for (i = 0; i < 8; ++i)
> +            env->fptags[i] = !((twd >> i) & 1);
> +        env->mxcsr = xsave->region[XSAVE_MXCSR];
> +        memcpy(env->fpregs, &xsave->region[XSAVE_ST_SPACE],
> +                sizeof env->fpregs);
> +        memcpy(env->xmm_regs, &xsave->region[XSAVE_XMM_SPACE],
> +                sizeof env->xmm_regs);
> +        env->xstate_bv = *(uint64_t *)&xsave->region[XSAVE_XSTATE_BV];
> +        memcpy(env->ymmh_regs, &xsave->region[XSAVE_YMMH_SPACE],
> +                sizeof env->ymmh_regs);
> +#ifdef KVM_CAP_XCRS
> +        if (kvm_check_extension(kvm_state, KVM_CAP_XCRS)) {
> +            kvm_get_xcrs(env, &xcrs);
> +            if (xcrs.xcrs[0].xcr == 0)
> +                env->xcr0 = xcrs.xcrs[0].value;
> +        }
> +#endif
> +    } else {
> +#endif
>      kvm_get_fpu(env, &fpu);
>      env->fpstt = (fpu.fsw >> 11) & 7;
>      env->fpus = fpu.fsw;
> @@ -974,6 +1064,9 @@ void kvm_arch_save_regs(CPUState *env)
>      memcpy(env->fpregs, fpu.fpr, sizeof env->fpregs);
>      memcpy(env->xmm_regs, fpu.xmm, sizeof env->xmm_regs);
>      env->mxcsr = fpu.mxcsr;
> +#ifdef KVM_CAP_XSAVE
> +    }
> +#endif
>  
>      kvm_get_sregs(env, &sregs);
>  
> diff --git a/qemu-kvm.c b/qemu-kvm.c
> index 96d458c..be1dac2 100644
> --- a/qemu-kvm.c
> +++ b/qemu-kvm.c
> @@ -503,6 +503,30 @@ int kvm_set_mpstate(CPUState *env, struct kvm_mp_state *mp_state)
>  }
>  #endif
>  
> +#ifdef KVM_CAP_XSAVE
> +int kvm_get_xsave(CPUState *env, struct kvm_xsave *xsave)
> +{
> +    return kvm_vcpu_ioctl(env, KVM_GET_XSAVE, xsave);
> +}
> +
> +int kvm_set_xsave(CPUState *env, struct kvm_xsave *xsave)
> +{
> +    return kvm_vcpu_ioctl(env, KVM_SET_XSAVE, xsave);
> +}
> +#endif
> +
> +#ifdef KVM_CAP_XCRS
> +int kvm_get_xcrs(CPUState *env, struct kvm_xcrs *xcrs)
> +{
> +    return kvm_vcpu_ioctl(env, KVM_GET_XCRS, xcrs);
> +}
> +
> +int kvm_set_xcrs(CPUState *env, struct kvm_xcrs *xcrs)
> +{
> +    return kvm_vcpu_ioctl(env, KVM_SET_XCRS, xcrs);
> +}
> +#endif
> +
>  static int handle_mmio(CPUState *env)
>  {
>      unsigned long addr = env->kvm_run->mmio.phys_addr;
> diff --git a/qemu-kvm.h b/qemu-kvm.h
> index 6f6c6d8..3ace503 100644
> --- a/qemu-kvm.h
> +++ b/qemu-kvm.h
> @@ -300,6 +300,34 @@ int kvm_get_mpstate(CPUState *env, struct kvm_mp_state *mp_state);
>  int kvm_set_mpstate(CPUState *env, struct kvm_mp_state *mp_state);
>  #endif
>  
> +#ifdef KVM_CAP_XSAVE
> +/*!
> + *  * \brief Read VCPU xsave state
> + *
> + */
> +int kvm_get_xsave(CPUState *env, struct kvm_xsave *xsave);
> +
> +/*!
> + *  * \brief Write VCPU xsave state
> + *
> + */
> +int kvm_set_xsave(CPUState *env, struct kvm_xsave *xsave);
> +#endif
> +
> +#ifdef KVM_CAP_XCRS
> +/*!
> + *  * \brief Read VCPU XCRs
> + *
> + */
> +int kvm_get_xcrs(CPUState *env, struct kvm_xcrs *xcrs);
> +
> +/*!
> + *  * \brief Write VCPU XCRs
> + *
> + */
> +int kvm_set_xcrs(CPUState *env, struct kvm_xcrs *xcrs);
> +#endif
> +
>  /*!
>   * \brief Simulate an external vectored interrupt
>   *


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