Commit 32d5fa80 authored by Chao Gao's avatar Chao Gao Committed by Ingo Molnar
Browse files

x86/fpu: 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: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: default avatarChao Gao <chao.gao@intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Reviewed-by: default avatarChang S. Bae <chang.seok.bae@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mitchell Levy <levymitchell0@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Samuel Holland <samuel.holland@sifive.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/kvm/af972fe5981b9e7101b64de43c7be0a8cc165323.camel@redhat.com/
Link: https://lore.kernel.org/r/20250506093740.2864458-3-chao.gao@intel.com
parent d8414603

arch/x86/include/asm/fpu/types.h

+0 −7
Original line number Diff line number Diff line
@@ -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.

	 */

arch/x86/kernel/fpu/core.c

+2 −5
Original line number Diff line number Diff line
@@ -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;

}