[PATCH 08/19] x86/fpu: Move xfd_update_state() to xstate.c and export symbol

Yang Zhong
2021-12-07T15:09:47Z

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

xfd_update_state() is the interface to update IA32_XFD and its per-cpu
cache. All callers of this interface are currently in fpu core. KVM only
indirectly triggers IA32_XFD update via a helper function
(fpu_swap_kvm_fpstate()) when switching between user fpu and guest fpu.

Supporting AMX in guest now requires KVM to directly update IA32_XFD
with the guest value (when emulating WRMSR) so XSAVE/XRSTOR can manage
XSTATE components correctly inside guest.

This patch moves xfd_update_state() from fpu/xstate.h to fpu/xstate.c
and export it for reference outside of fpu core.

Signed-off-by: Jing Liu <jing2.liu@intel.com>
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
---
arch/x86/include/asm/fpu/api.h | 2 ++
arch/x86/kernel/fpu/xstate.c | 12 ++++++++++++
arch/x86/kernel/fpu/xstate.h | 14 +-------------
3 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h
index 7532f73c82a6..999d89026be9 100644
--- a/arch/x86/include/asm/fpu/api.h
+++ b/arch/x86/include/asm/fpu/api.h
@@ -131,8 +131,10 @@ DECLARE_PER_CPU(struct fpu *, fpu_fpregs_owner_ctx);
/* Process cleanup */
#ifdef CONFIG_X86_64
extern void fpstate_free(struct fpu *fpu);
+extern void xfd_update_state(struct fpstate *fpstate);
#else
static inline void fpstate_free(struct fpu *fpu) { }
+static void xfd_update_state(struct fpstate *fpstate) { }
#endif

/* fpstate-related functions which are exported to KVM */
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index fe3d8ed3db0e..3c39789deeb9 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1750,6 +1750,18 @@ int xfd_enable_guest_features(struct fpu_guest *guest_fpu)
return __xfd_enable_feature(xfd_err, guest_fpu);
}

+void xfd_update_state(struct fpstate *fpstate)
+{
+ if (fpu_state_size_dynamic()) {
+ u64 xfd = fpstate->xfd;
+
+ if (__this_cpu_read(xfd_state) != xfd) {
+ wrmsrl(MSR_IA32_XFD, xfd);
+ __this_cpu_write(xfd_state, xfd);
+ }
+ }
+}
+EXPORT_SYMBOL_GPL(xfd_update_state);
#else /* CONFIG_X86_64 */
static inline int xstate_request_perm(unsigned long idx, bool guest)
{
diff --git a/arch/x86/kernel/fpu/xstate.h b/arch/x86/kernel/fpu/xstate.h
index 3254e2b5f17f..651bd29977b9 100644
--- a/arch/x86/kernel/fpu/xstate.h
+++ b/arch/x86/kernel/fpu/xstate.h
@@ -149,19 +149,7 @@ static inline void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rs
#endif

#ifdef CONFIG_X86_64
-static inline void xfd_update_state(struct fpstate *fpstate)
-{
- if (fpu_state_size_dynamic()) {
- u64 xfd = fpstate->xfd;
-
- if (__this_cpu_read(xfd_state) != xfd) {
- wrmsrl(MSR_IA32_XFD, xfd);
- __this_cpu_write(xfd_state, xfd);
- }
- }
-}
-#else
-static inline void xfd_update_state(struct fpstate *fpstate) { }
+extern void xfd_update_state(struct fpstate *fpstate);
#endif

/*