[PATCH v6 05/25] x86/fpu/xstate: Remove kernel dynamic xfeatures from kernel default_features

[Yang Weijiang]

The kernel dynamic xfeatures are supported by host, i.e., they're enabled
in xsaves/xrstors operating xfeature set (XCR0 | XSS), but the corresponding
CPU features are disabled for the time-being in host kernel so the bits are
not necessarily set by default.

Remove the bits from fpu_kernel_cfg.default_features so that the bits in
xstate_bv and xcomp_bv are cleared and xsaves/xrstors can be optimized by HW
for normal fpstate.

Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
---
 arch/x86/kernel/fpu/xstate.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index eaec05bc1b3c..4753c677e2e1 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -845,6 +845,7 @@ void __init fpu__init_system_xstate(unsigned int legacy_size)
 	/* Clean out dynamic features from default */
 	fpu_kernel_cfg.default_features = fpu_kernel_cfg.max_features;
 	fpu_kernel_cfg.default_features &= ~XFEATURE_MASK_USER_DYNAMIC;
+	fpu_kernel_cfg.default_features &= ~fpu_kernel_dynamic_xfeatures;
 
 	fpu_user_cfg.default_features = fpu_user_cfg.max_features;
 	fpu_user_cfg.default_features &= ~XFEATURE_MASK_USER_DYNAMIC;
-- 
2.27.0