x86/EFI: further correct FPU state handling around runtime calls

We must not leave a vCPU with CR0.TS clear when it is not in fully eager
mode and has not touched non-lazy state. Instead of adding a 3rd
invocation of stts() to vcpu_restore_fpu_eager(), consolidate all of
them into a single one done at the end of the function.

Rename the function at the same time to better reflect its purpose, as
the patches touches all of its occurences anyway.

The new function parameter is not really well named, but
"need_stts_if_not_fully_eager" seemed excessive to me.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
master commit: 23839a0fa0bbe78c174cd2bb49083e153f0f99df
master date: 2018-06-26 15:23:08 +0200

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 0ca820a00a42e0cdb13ddbc640a7c924f057bfae..9850a782ec84071384547b367c4f0580af135dd6 100644 (file)
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -1636,7 +1636,7 @@ static void __context_switch(void)
             if ( cpu_has_xsaves && is_hvm_vcpu(n) )
                 set_msr_xss(n->arch.hvm_vcpu.msr_xss);
         }
-        vcpu_restore_fpu_eager(n);
+        vcpu_restore_fpu_nonlazy(n, false);
         nd->arch.ctxt_switch->to(n);
     }
 

diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index 7ecee12ffc353c1767de11c9affe723ecbce8e6c..cac968f48e84c50504cf7d97be6fe8bd699675a2 100644 (file)
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -2147,7 +2147,7 @@ static void hvmemul_put_fpu(
          *   by hvmemul_get_fpu().
          */
         if ( curr->arch.fully_eager_fpu )
-            vcpu_restore_fpu_eager(curr);
+            vcpu_restore_fpu_nonlazy(curr, false);
         else
         {
             curr->fpu_dirtied = false;

diff --git a/xen/arch/x86/i387.c b/xen/arch/x86/i387.c
index 9c752732a3afaaef98708e653cb97c80c517b294..a1d128dd949f76324dceec12df2eb867d612dda9 100644 (file)
--- a/xen/arch/x86/i387.c
+++ b/xen/arch/x86/i387.c
@@ -206,11 +206,11 @@ static inline void fpu_fxsave(struct vcpu *v)
 /*       VCPU FPU Functions    */
 /*******************************/
 /* Restore FPU state whenever VCPU is schduled in. */
-void vcpu_restore_fpu_eager(struct vcpu *v)
+void vcpu_restore_fpu_nonlazy(struct vcpu *v, bool need_stts)
 {
     /* Restore nonlazy extended state (i.e. parts not tracked by CR0.TS). */
     if ( !v->arch.fully_eager_fpu && !v->arch.nonlazy_xstate_used )
-        return;
+        goto maybe_stts;
 
     ASSERT(!is_idle_vcpu(v));
 
@@ -233,14 +233,17 @@ void vcpu_restore_fpu_eager(struct vcpu *v)
         v->fpu_dirtied = 1;
 
         /* Xen doesn't need TS set, but the guest might. */
-        if ( is_pv_vcpu(v) && (v->arch.pv_vcpu.ctrlreg[0] & X86_CR0_TS) )
-            stts();
+        need_stts = is_pv_vcpu(v) && (v->arch.pv_vcpu.ctrlreg[0] & X86_CR0_TS);
     }
     else
     {
         fpu_xrstor(v, XSTATE_NONLAZY);
-        stts();
+        need_stts = true;
     }
+
+ maybe_stts:
+    if ( need_stts )
+        stts();
 }
 
 /* 

diff --git a/xen/common/efi/runtime.c b/xen/common/efi/runtime.c
index aad3ab57d2373a3ad7ef7a729d7b73f4d1aadde1..3d118d571d4e0798f9b0780087390c3aeaa5d97b 100644 (file)
--- a/xen/common/efi/runtime.c
+++ b/xen/common/efi/runtime.c
@@ -135,7 +135,7 @@ void efi_rs_leave(struct efi_rs_state *state)
     irq_exit();
     efi_rs_on_cpu = NR_CPUS;
     spin_unlock(&efi_rs_lock);
-    vcpu_restore_fpu_eager(curr);
+    vcpu_restore_fpu_nonlazy(curr, true);
 }
 
 bool efi_rs_using_pgtables(void)

diff --git a/xen/include/asm-x86/i387.h b/xen/include/asm-x86/i387.h
index 7cfa215d303b273a832b4ea512aef9e11023a40a..243de672eb55061d65d7ddfbacd048820d95dba9 100644 (file)
--- a/xen/include/asm-x86/i387.h
+++ b/xen/include/asm-x86/i387.h
@@ -28,7 +28,7 @@ struct ix87_env {
     uint16_t fds, _res6;
 };
 
-void vcpu_restore_fpu_eager(struct vcpu *v);
+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);