[PATCH v6 2/7] x86/fpu: Drop @perm from guest pseudo FPU container

[Chao Gao <chao.gao@intel.com>]

Remove @perm from the guest pseudo FPU container. The field is
initialized during allocation and never used later.

Rename fpu_init_guest_permissions() to show that its sole purpose is to
lock down guest permissions.

Suggested-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Chang S. Bae <chang.seok.bae@intel.com>
Link: https://lore.kernel.org/kvm/af972fe5981b9e7101b64de43c7be0a8cc165323.camel@redhat.com/
---
v6: add Chang's Reviewed-by
v5: drop the useless fpu_guest argument (Chang)
---
 arch/x86/include/asm/fpu/types.h | 7 -------
 arch/x86/kernel/fpu/core.c       | 7 ++-----
 2 files changed, 2 insertions(+), 12 deletions(-)

diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h
index e64db0eb9d27..1c94121acd3d 100644
--- a/arch/x86/include/asm/fpu/types.h
+++ b/arch/x86/include/asm/fpu/types.h
@@ -535,13 +535,6 @@ struct fpu_guest {
 	 */
 	u64				xfeatures;
 
-	/*
-	 * @perm:			xfeature bitmap of features which are
-	 *				permitted to be enabled for the guest
-	 *				vCPU.
-	 */
-	u64				perm;
-
 	/*
 	 * @xfd_err:			Save the guest value.
 	 */
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 105b1b80d88d..1cda5b78540b 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -212,7 +212,7 @@ void fpu_reset_from_exception_fixup(void)
 #if IS_ENABLED(CONFIG_KVM)
 static void __fpstate_reset(struct fpstate *fpstate, u64 xfd);
 
-static void fpu_init_guest_permissions(struct fpu_guest *gfpu)
+static void fpu_lock_guest_permissions(void)
 {
 	struct fpu_state_perm *fpuperm;
 	u64 perm;
@@ -228,8 +228,6 @@ static void fpu_init_guest_permissions(struct fpu_guest *gfpu)
 	WRITE_ONCE(fpuperm->__state_perm, perm | FPU_GUEST_PERM_LOCKED);
 
 	spin_unlock_irq(&current->sighand->siglock);
-
-	gfpu->perm = perm & ~FPU_GUEST_PERM_LOCKED;
 }
 
 bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu)
@@ -250,7 +248,6 @@ bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu)
 
 	gfpu->fpstate		= fpstate;
 	gfpu->xfeatures		= fpu_kernel_cfg.default_features;
-	gfpu->perm		= fpu_kernel_cfg.default_features;
 
 	/*
 	 * KVM sets the FP+SSE bits in the XSAVE header when copying FPU state
@@ -265,7 +262,7 @@ bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu)
 	if (WARN_ON_ONCE(fpu_user_cfg.default_size > gfpu->uabi_size))
 		gfpu->uabi_size = fpu_user_cfg.default_size;
 
-	fpu_init_guest_permissions(gfpu);
+	fpu_lock_guest_permissions();
 
 	return true;
 }
-- 
2.47.1