linux-kernel - [PATCH 5/5] KVM: x86: kvm_fpu_get() is fpregs_lock_and

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Message-ID: <20251224001249.1041934-6-pbonzini@redhat.com>
Date: Wed, 24 Dec 2025 01:12:49 +0100
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org
Cc: seanjc@...gle.com,
	x86@...nel.org
Subject: [PATCH 5/5] KVM: x86: kvm_fpu_get() is fpregs_lock_and_load()

The only difference is the usage of switch_fpu_return() vs.
fpregs_restore_userregs().  In turn, these are only different
if there is no FPU at all, but KVM requires one.  Therefore use the
pre-made export---the code is simpler and there is no functional change.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kernel/fpu/core.c | 2 +--
 arch/x86/kvm/fpu.h         | 6 +-----
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index ff17c96d290a..6571952c6ef1 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -846,7 +846,6 @@ void switch_fpu_return(void)
 
 	fpregs_restore_userregs();
 }
-EXPORT_SYMBOL_FOR_KVM(switch_fpu_return);
 
 void fpregs_lock_and_load(void)
 {
@@ -865,6 +864,7 @@ void fpregs_lock_and_load(void)
 
 	fpregs_assert_state_consistent();
 }
+EXPORT_SYMBOL_FOR_KVM(fpregs_lock_and_load);
 
 void fpu_load_guest_fpstate(struct fpu_guest *gfpu)
 {
@@ -899,7 +899,6 @@ void fpregs_assert_state_consistent(void)
 
 	WARN_ON_FPU(!fpregs_state_valid(fpu, smp_processor_id()));
 }
-EXPORT_SYMBOL_FOR_KVM(fpregs_assert_state_consistent);
 #endif
 
 void fpregs_mark_activate(void)
diff --git a/arch/x86/kvm/fpu.h b/arch/x86/kvm/fpu.h
index f898781b6a06..b6a03d8fa8af 100644
--- a/arch/x86/kvm/fpu.h
+++ b/arch/x86/kvm/fpu.h
@@ -149,11 +149,7 @@ static inline void _kvm_write_mmx_reg(int reg, const u64 *data)
 
 static inline void kvm_fpu_get(void)
 {
-	fpregs_lock();
-
-	fpregs_assert_state_consistent();
-	if (test_thread_flag(TIF_NEED_FPU_LOAD))
-		switch_fpu_return();
+	fpregs_lock_and_load();
 }
 
 static inline void kvm_fpu_put(void)
-- 
2.52.0