[PATCH 05/19] x86/fpu: Move xfd initialization out of __fpstate_reset() to the callers

Yang Zhong
2021-12-07T15:09:29Z

From: Jing Liu <jing2.liu@intel.com>

vCPU threads are different from native tasks regarding to the initial
xfd value. While all native tasks follow a fixed value (init_fpstate::xfd)
defined by fpu core, vCPU threads need to obey the reset value
(i.e. ZERO) defined by the spec, to meet the expectation of the guest.

Move xfd initialization out of __fpstate_reset() to the callers for
choosing a specific value.

Signed-off-by: Jing Liu <jing2.liu@intel.com>
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
---
arch/x86/kernel/fpu/core.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index fe592799508c..fae44fa27cdb 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -231,6 +231,7 @@ bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu)
if (!fpstate)
return false;

+ /* Leave xfd to 0 (the reset value defined by spec) */
__fpstate_reset(fpstate);
fpstate_init_user(fpstate);
fpstate->is_valloc = true;
@@ -461,7 +462,6 @@ static void __fpstate_reset(struct fpstate *fpstate)
fpstate->user_size = fpu_user_cfg.default_size;
fpstate->xfeatures = fpu_kernel_cfg.default_features;
fpstate->user_xfeatures = fpu_user_cfg.default_features;
- fpstate->xfd = init_fpstate.xfd;
}

void fpstate_reset(struct fpu *fpu)
@@ -469,6 +469,7 @@ void fpstate_reset(struct fpu *fpu)
/* Set the fpstate pointer to the default fpstate */
fpu->fpstate = &fpu->__fpstate;
__fpstate_reset(fpu->fpstate);
+ fpu->fpstate->xfd = init_fpstate.xfd;

/* Initialize the permission related info in fpu */
fpu->perm.__state_perm = fpu_kernel_cfg.default_features;