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x86/fpu: Remove xfd argument from __fpstate_reset()

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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: Sean Christopherson <seanjc@google.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: John 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
This commit is contained in:
Chao Gao 2025-05-22 08:10:07 -07:00 committed by Dave Hansen
parent 509e880b77
commit fafb29e18d
1 changed files with 9 additions and 6 deletions
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15
arch/x86/kernel/fpu/core.c
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@ -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;