From: Wei Liu <wei.liu2@citrix.com>
Remove lazy FPU support from the #NM exception handler used by PV
guests since fully_eager_fpu is now always true.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
---
In v2:
* Tweaked the commit message
* Crash the guest rather than host if the guest register is in an
unexpected state.
* Reword a comment
* Allow tail-call optimization
xen/arch/x86/i387.c | 24 ------------------------
xen/arch/x86/include/asm/i387.h | 1 -
xen/arch/x86/pv/misc-hypercalls.c | 3 +--
xen/arch/x86/traps.c | 20 +++++++++++++-------
4 files changed, 14 insertions(+), 34 deletions(-)
diff --git a/xen/arch/x86/i387.c b/xen/arch/x86/i387.c
index 954ba3b1799b..7da731865f73 100644
--- a/xen/arch/x86/i387.c
+++ b/xen/arch/x86/i387.c
@@ -234,30 +234,6 @@ void vcpu_restore_fpu_nonlazy(struct vcpu *v, bool need_stts)
stts();
}
-/*
- * Restore FPU state when #NM is triggered.
- */
-void vcpu_restore_fpu_lazy(struct vcpu *v)
-{
- ASSERT(!is_idle_vcpu(v));
-
- /* Avoid recursion. */
- clts();
-
- if ( v->fpu_dirtied )
- return;
-
- ASSERT(!v->arch.fully_eager_fpu);
-
- if ( cpu_has_xsave )
- fpu_xrstor(v, XSTATE_LAZY);
- else
- fpu_fxrstor(v);
-
- v->fpu_initialised = 1;
- v->fpu_dirtied = 1;
-}
-
/*
* On each context switch, save the necessary FPU info of VCPU being switch
* out. It dispatches saving operation based on CPU's capability.
diff --git a/xen/arch/x86/include/asm/i387.h b/xen/arch/x86/include/asm/i387.h
index 652d7ad2deb6..da0c7e945f95 100644
--- a/xen/arch/x86/include/asm/i387.h
+++ b/xen/arch/x86/include/asm/i387.h
@@ -28,7 +28,6 @@ struct ix87_env {
};
void vcpu_restore_fpu_nonlazy(struct vcpu *v, bool need_stts);
-void vcpu_restore_fpu_lazy(struct vcpu *v);
void vcpu_save_fpu(struct vcpu *v);
void save_fpu_enable(void);
int vcpu_init_fpu(struct vcpu *v);
diff --git a/xen/arch/x86/pv/misc-hypercalls.c b/xen/arch/x86/pv/misc-hypercalls.c
index 7e915d86b724..34a0717540a9 100644
--- a/xen/arch/x86/pv/misc-hypercalls.c
+++ b/xen/arch/x86/pv/misc-hypercalls.c
@@ -42,8 +42,7 @@ long do_fpu_taskswitch(int set)
else
{
v->arch.pv.ctrlreg[0] &= ~X86_CR0_TS;
- if ( v->fpu_dirtied )
- clts();
+ clts();
}
return 0;
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index b6b119769722..0565c576ecd6 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -2045,15 +2045,21 @@ void asmlinkage do_device_not_available(struct cpu_user_regs *regs)
}
#ifdef CONFIG_PV
- vcpu_restore_fpu_lazy(curr);
-
- if ( curr->arch.pv.ctrlreg[0] & X86_CR0_TS )
+ if ( !(curr->arch.pv.ctrlreg[0] & X86_CR0_TS) )
{
- pv_inject_hw_exception(X86_EXC_NM, X86_EVENT_NO_EC);
- curr->arch.pv.ctrlreg[0] &= ~X86_CR0_TS;
+ ASSERT_UNREACHABLE();
+ domain_crash(curr->domain);
+ return;
}
- else
- TRACE_TIME(TRC_PV_MATH_STATE_RESTORE);
+
+ /*
+ * For better or worse, Xen's ABI with PV guests always clears TS on an #NM
+ * exception. Classic-xen Linux depends on this.
+ */
+ clts();
+ curr->arch.pv.ctrlreg[0] &= ~X86_CR0_TS;
+
+ pv_inject_hw_exception(X86_EXC_NM, X86_EVENT_NO_EC);
#else
ASSERT_UNREACHABLE();
#endif
--
2.53.0