[patch 04/21] x86/fpu: Replace KVMs xstate component clearing

[Thomas Gleixner <tglx@linutronix.de>]

In order to prepare for the support of dynamically enabled FPU features,
move the clearing of xstate components to the FPU core code.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org
---
 arch/x86/include/asm/fpu/api.h    |    1 +
 arch/x86/include/asm/fpu/xstate.h |    1 -
 arch/x86/kernel/fpu/xstate.c      |   12 +++++++++++-
 arch/x86/kernel/fpu/xstate.h      |    2 ++
 arch/x86/kvm/x86.c                |   14 +++++---------
 5 files changed, 19 insertions(+), 11 deletions(-)

--- a/arch/x86/include/asm/fpu/api.h
+++ b/arch/x86/include/asm/fpu/api.h
@@ -132,6 +132,7 @@ DECLARE_PER_CPU(struct fpu *, fpu_fpregs
 
 /* fpstate-related functions which are exported to KVM */
 extern void fpu_init_fpstate_user(struct fpu *fpu);
+extern void fpstate_clear_xstate_component(struct fpstate *fps, unsigned int xfeature);
 
 /* KVM specific functions */
 extern void fpu_swap_kvm_fpu(struct fpu *save, struct fpu *rstor, u64 restore_mask);
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -128,7 +128,6 @@ extern u64 xstate_fx_sw_bytes[USER_XSTAT
 extern void __init update_regset_xstate_info(unsigned int size,
 					     u64 xstate_mask);
 
-void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr);
 int xfeature_size(int xfeature_nr);
 int copy_uabi_from_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf);
 int copy_sigframe_from_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf);
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -908,7 +908,6 @@ void *get_xsave_addr(struct xregs_state
 
 	return __raw_xsave_addr(xsave, xfeature_nr);
 }
-EXPORT_SYMBOL_GPL(get_xsave_addr);
 
 #ifdef CONFIG_ARCH_HAS_PKEYS
 
@@ -1257,6 +1256,17 @@ void xrstors(struct xregs_state *xstate,
 	WARN_ON_ONCE(err);
 }
 
+#if IS_ENABLED(CONFIG_KVM)
+void fpstate_clear_xstate_component(struct fpstate *fps, unsigned int xfeature)
+{
+	void *addr = get_xsave_addr(&fps->regs.xsave, xfeature);
+
+	if (addr)
+		memset(addr, 0, xstate_sizes[xfeature]);
+}
+EXPORT_SYMBOL_GPL(fpstate_clear_xstate_component);
+#endif
+
 #ifdef CONFIG_PROC_PID_ARCH_STATUS
 /*
  * Report the amount of time elapsed in millisecond since last AVX512
--- a/arch/x86/kernel/fpu/xstate.h
+++ b/arch/x86/kernel/fpu/xstate.h
@@ -21,6 +21,8 @@ extern void __copy_xstate_to_uabi_buf(st
 extern void fpu__init_cpu_xstate(void);
 extern void fpu__init_system_xstate(void);
 
+extern void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr);
+
 /* XSAVE/XRSTOR wrapper functions */
 
 #ifdef CONFIG_X86_64
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10689,7 +10689,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcp
 	vcpu->arch.apf.halted = false;
 
 	if (vcpu->arch.guest_fpu && kvm_mpx_supported()) {
-		void *mpx_state_buffer;
+		struct fpstate *fpstate = vcpu->arch.guest_fpu->fpstate;
 
 		/*
 		 * To avoid have the INIT path from kvm_apic_has_events() that be
@@ -10697,14 +10697,10 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcp
 		 */
 		if (init_event)
 			kvm_put_guest_fpu(vcpu);
-		mpx_state_buffer = get_xsave_addr(&vcpu->arch.guest_fpu->state.xsave,
-					XFEATURE_BNDREGS);
-		if (mpx_state_buffer)
-			memset(mpx_state_buffer, 0, sizeof(struct mpx_bndreg_state));
-		mpx_state_buffer = get_xsave_addr(&vcpu->arch.guest_fpu->state.xsave,
-					XFEATURE_BNDCSR);
-		if (mpx_state_buffer)
-			memset(mpx_state_buffer, 0, sizeof(struct mpx_bndcsr));
+
+		fpstate_clear_xstate_component(fpstate, XFEATURE_BNDREGS);
+		fpstate_clear_xstate_component(fpstate, XFEATURE_BNDCSR);
+
 		if (init_event)
 			kvm_load_guest_fpu(vcpu);
 	}