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    Subject[PATCH v4 17/21] x86/fpu: Add uabi_size to guest_fpu
    Date
    From: Thomas Gleixner <tglx@linutronix.de>

    Userspace needs to inquire KVM about the buffer size to work
    with the new KVM_SET_XSAVE and KVM_GET_XSAVE2. Add the size info
    to guest_fpu for KVM to access.

    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: Wei Wang <wei.w.wang@intel.com>
    Signed-off-by: Jing Liu <jing2.liu@intel.com>
    Signed-off-by: Yang Zhong <yang.zhong@intel.com>
    ---
    arch/x86/include/asm/fpu/types.h | 5 +++++
    arch/x86/kernel/fpu/core.c | 1 +
    arch/x86/kernel/fpu/xstate.c | 1 +
    3 files changed, 7 insertions(+)

    diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h
    index 3795d0573773..eb7cd1139d97 100644
    --- a/arch/x86/include/asm/fpu/types.h
    +++ b/arch/x86/include/asm/fpu/types.h
    @@ -522,6 +522,11 @@ struct fpu_guest {
    */
    u64 xfd_err;

    + /*
    + * @uabi_size: Size required for save/restore
    + */
    + unsigned int uabi_size;
    +
    /*
    * @fpstate: Pointer to the allocated guest fpstate
    */
    diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
    index 3daea097c618..89d679cc819b 100644
    --- a/arch/x86/kernel/fpu/core.c
    +++ b/arch/x86/kernel/fpu/core.c
    @@ -240,6 +240,7 @@ bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu)
    gfpu->fpstate = fpstate;
    gfpu->xfeatures = fpu_user_cfg.default_features;
    gfpu->perm = fpu_user_cfg.default_features;
    + gfpu->uabi_size = fpu_user_cfg.default_size;
    fpu_init_guest_permissions(gfpu);

    return true;
    diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
    index 0c0b2323cdec..10fe072f1c92 100644
    --- a/arch/x86/kernel/fpu/xstate.c
    +++ b/arch/x86/kernel/fpu/xstate.c
    @@ -1545,6 +1545,7 @@ static int fpstate_realloc(u64 xfeatures, unsigned int ksize,
    newfps->is_confidential = curfps->is_confidential;
    newfps->in_use = curfps->in_use;
    guest_fpu->xfeatures |= xfeatures;
    + guest_fpu->uabi_size = usize;
    }

    fpregs_lock();
    \
     
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