[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH] target-i386/kvm.c: Fix the order of FPU registe
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] target-i386/kvm.c: Fix the order of FPU registers in xsave |
Date: |
Wed, 10 Feb 2016 15:17:24 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0 |
On 10/02/2016 12:02, Asia Slowinska wrote:
> Stick to the expected order of the FPU registers in xsave (as specified
> in the
> Intel manual.) Otherwise, instructions loading the FPU state don't set
> it up
> correctly.
>
> To set up FPU, software needs to provide a buffer of 80 bytes
> storing 8 FPU registers. They are organized in a stack. FPU assumes that the
> first field of the buffer is ST0, then ST1, and so on. QEMU maintains a
> circular buffer. When preparing these 80 bytes for KVM, QEMU just uses
> memcpy
> instead of copying the elements in a proper order.
>
> Signed-off-by: Asia Slowinska <address@hidden <mailto:address@hidden>>
> ---
> target-i386/kvm.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/target-i386/kvm.c b/target-i386/kvm.c
> index 94024bc..c77fe73 100644
> --- a/target-i386/kvm.c
> +++ b/target-i386/kvm.c
> @@ -1325,8 +1325,10 @@ static int kvm_put_xsave(X86CPU *cpu)
> xsave->region[XSAVE_FTW_FOP] = (uint32_t)(env->fpop << 16) + twd;
> memcpy(&xsave->region[XSAVE_CWD_RIP], &env->fpip, sizeof(env->fpip));
> memcpy(&xsave->region[XSAVE_CWD_RDP], &env->fpdp, sizeof(env->fpdp));
> - memcpy(&xsave->region[XSAVE_ST_SPACE], env->fpregs,
> - sizeof env->fpregs);
> + for (i = 0; i < 8; i++) {
> + memcpy(&xsave_region[HXSAVE_ST_SPACE + i * 4],
> + &env->fpregs[(env->fpstt + i) & 7], 16);
> + }
> xsave->region[XSAVE_MXCSR] = env->mxcsr;
> *(uint64_t *)&xsave->region[XSAVE_XSTATE_BV] = env->xstate_bv;
> memcpy(&xsave->region[XSAVE_BNDREGS], env->bnd_regs,
> @@ -1745,8 +1747,10 @@ static int kvm_get_xsave(X86CPU *cpu)
> memcpy(&env->fpip, &xsave->region[XSAVE_CWD_RIP], sizeof(env->fpip));
> memcpy(&env->fpdp, &xsave->region[XSAVE_CWD_RDP], sizeof(env->fpdp));
> env->mxcsr = xsave->region[XSAVE_MXCSR];
> - memcpy(env->fpregs, &xsave->region[XSAVE_ST_SPACE],
> - sizeof env->fpregs);
> + for (i = 0; i < 8; i++) {
> + memcpy(&env->fpregs[(env->fpstt + i) & 7],
> + &xsave_region[HXSAVE_ST_SPACE + i * 4], 16);
Hi, the patch is missing a definition of HXSAVE_ST_SPACE.
Thanks,
Paolo
> + }
> env->xstate_bv = *(uint64_t *)&xsave->region[XSAVE_XSTATE_BV];
> memcpy(env->bnd_regs, &xsave->region[XSAVE_BNDREGS],
> sizeof env->bnd_regs);
> --
> 1.9.1
>
>