x86/fpu: Add uabi_size to guest_fpu

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>
Message-Id: <20220105123532.12586-18-yang.zhong@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h
index 3795d05..eb7cd11 100644 (file)
--- a/arch/x86/include/asm/fpu/types.h
+++ b/arch/x86/include/asm/fpu/types.h
@@ -523,6 +523,11 @@ struct fpu_guest {
        u64                             xfd_err;
 
        /*
+        * @uabi_size:                  Size required for save/restore
+        */
+       unsigned int                    uabi_size;
+
+       /*
         * @fpstate:                    Pointer to the allocated guest fpstate
         */
        struct fpstate                  *fpstate;

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 271fd5b..de8e8c2 100644 (file)
--- 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 0c0b232..10fe072 100644 (file)
--- 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();