linux-kernel - [PATCH v3 02/10] x86/fpu/xstate: Drop @perm from guest pseudo FPU container

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Message-ID: <20250307164123.1613414-3-chao.gao@intel.com>
Date: Sat,  8 Mar 2025 00:41:15 +0800
From: Chao Gao <chao.gao@...el.com>
To: chao.gao@...el.com,
	tglx@...utronix.de,
	dave.hansen@...el.com,
	x86@...nel.org,
	seanjc@...gle.com,
	pbonzini@...hat.com,
	linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org
Cc: peterz@...radead.org,
	rick.p.edgecombe@...el.com,
	weijiang.yang@...el.com,
	john.allen@....com,
	bp@...en8.de,
	Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH v3 02/10] x86/fpu/xstate: Drop @perm from guest pseudo FPU container

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@...hat.com>
Signed-off-by: Chao Gao <chao.gao@...el.com>
---
 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 46cc263f9f4f..9f9ed406b179 100644
--- a/arch/x86/include/asm/fpu/types.h
+++ b/arch/x86/include/asm/fpu/types.h
@@ -526,13 +526,6 @@ 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 1209c7aebb21..dc169f3d336d 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -195,7 +195,7 @@ 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(struct fpu_guest *gfpu)
 {
 	struct fpu_state_perm *fpuperm;
 	u64 perm;
@@ -211,8 +211,6 @@ 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)
@@ -233,7 +231,6 @@ 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;
 
 	/*
 	 * KVM sets the FP+SSE bits in the XSAVE header when copying FPU state
@@ -248,7 +245,7 @@ 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(gfpu);
 
 	return true;
 }
-- 
2.46.1