Commit 36487e62 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Paolo Bonzini
Browse files

x86/fpu: Prepare guest FPU for dynamically enabled FPU features 



To support dynamically enabled FPU features for guests prepare the guest
pseudo FPU container to keep track of the currently enabled xfeatures and
the guest permissions.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarJing Liu <jing2.liu@intel.com>
Signed-off-by: default avatarYang Zhong <yang.zhong@intel.com>
Message-Id: <20220105123532.12586-3-yang.zhong@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 980fe2fd

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

+13 −0
Original line number Diff line number Diff line
@@ -504,6 +504,19 @@ struct fpu { 
 * Guest pseudo FPU container

 */

struct fpu_guest {

	/*

	 * @xfeatures:			xfeature bitmap of features which are

	 *				currently enabled for the guest vCPU.

	 */

	u64				xfeatures;



	/*

	 * @perm:			xfeature bitmap of features which are

	 *				permitted to be enabled for the guest

	 *				vCPU.

	 */

	u64				perm;



	/*

	 * @fpstate:			Pointer to the allocated guest fpstate

	 */

arch/x86/kernel/fpu/core.c

+25 −1
Original line number Diff line number Diff line
@@ -201,6 +201,26 @@ void fpu_reset_from_exception_fixup(void) 
#if IS_ENABLED(CONFIG_KVM)

static void __fpstate_reset(struct fpstate *fpstate);



static void fpu_init_guest_permissions(struct fpu_guest *gfpu)

{

	struct fpu_state_perm *fpuperm;

	u64 perm;



	if (!IS_ENABLED(CONFIG_X86_64))

		return;



	spin_lock_irq(&current->sighand->siglock);

	fpuperm = &current->group_leader->thread.fpu.guest_perm;

	perm = fpuperm->__state_perm;



	/* First fpstate allocation locks down permissions. */

	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)

{

	struct fpstate *fpstate;
@@ -217,6 +237,10 @@ bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu) 
	fpstate->is_guest	= true;



	gfpu->fpstate		= fpstate;

	gfpu->xfeatures		= fpu_user_cfg.default_features;

	gfpu->perm		= fpu_user_cfg.default_features;

	fpu_init_guest_permissions(gfpu);



	return true;

}

EXPORT_SYMBOL_GPL(fpu_alloc_guest_fpstate);