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

Thomas Gleixner
2021-10-13T14:55:37Z

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);
}