Commit fafb29e1 authored by Chao Gao's avatar Chao Gao Committed by Dave Hansen
Browse files

x86/fpu: Remove xfd argument from __fpstate_reset() 



The initial values for fpstate::xfd differ between guest and host fpstates.
Currently, the initial values are passed as an argument to
__fpstate_reset(). But, __fpstate_reset() already assigns different default
features and sizes based on the type of fpstates (i.e., guest or host). So,
handle fpstate::xfd in a similar way to highlight the differences in the
initial xfd value between guest and host fpstates

Suggested-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarChao Gao <chao.gao@intel.com>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: default avatarJohn Allen <john.allen@amd.com>
Link: https://lore.kernel.org/all/aBuf7wiiDT0Wflhk@google.com/
Link: https://lore.kernel.org/all/20250522151031.426788-5-chao.gao%40intel.com
parent 509e880b

arch/x86/kernel/fpu/core.c

+9 −6
Original line number Diff line number Diff line
@@ -218,7 +218,7 @@ void fpu_reset_from_exception_fixup(void) 
}



#if IS_ENABLED(CONFIG_KVM)

static void __fpstate_reset(struct fpstate *fpstate, u64 xfd);

static void __fpstate_reset(struct fpstate *fpstate);



static void fpu_lock_guest_permissions(void)

{
@@ -253,8 +253,7 @@ bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu) 
	fpstate->is_valloc	= true;

	fpstate->is_guest	= true;



	/* Leave xfd to 0 (the reset value defined by spec) */

	__fpstate_reset(fpstate, 0);

	__fpstate_reset(fpstate);

	fpstate_init_user(fpstate);



	gfpu->fpstate		= fpstate;
@@ -545,7 +544,7 @@ void fpstate_init_user(struct fpstate *fpstate) 
		fpstate_init_fstate(fpstate);

}



static void __fpstate_reset(struct fpstate *fpstate, u64 xfd)

static void __fpstate_reset(struct fpstate *fpstate)

{

	/*

	 * Supervisor features (and thus sizes) may diverge between guest
@@ -553,25 +552,29 @@ static void __fpstate_reset(struct fpstate *fpstate, u64 xfd) 
	 * for guests despite not being utilized by the host. User

	 * features and sizes are always identical, which allows for

	 * common guest and userspace ABI.

	 *

	 * For the host, set XFD to the kernel's desired initialization

	 * value. For guests, set XFD to its architectural RESET value.

	 */

	if (fpstate->is_guest) {

		fpstate->size		= guest_default_cfg.size;

		fpstate->xfeatures	= guest_default_cfg.features;

		fpstate->xfd		= 0;

	} else {

		fpstate->size		= fpu_kernel_cfg.default_size;

		fpstate->xfeatures	= fpu_kernel_cfg.default_features;

		fpstate->xfd		= init_fpstate.xfd;

	}



	fpstate->user_size	= fpu_user_cfg.default_size;

	fpstate->user_xfeatures	= fpu_user_cfg.default_features;

	fpstate->xfd		= xfd;

}



void fpstate_reset(struct fpu *fpu)

{

	/* Set the fpstate pointer to the default fpstate */

	fpu->fpstate = &fpu->__fpstate;

	__fpstate_reset(fpu->fpstate, init_fpstate.xfd);

	__fpstate_reset(fpu->fpstate);



	/* Initialize the permission related info in fpu */

	fpu->perm.__state_perm		= fpu_kernel_cfg.default_features;