[Xen-devel] [PATCH v3 3/5] x86/HVM: move NOFLUSH handling out of hvm_set_cr3()

[Jan Beulich <jbeulich@xxxxxxxx>]

The bit is meaningful only for MOV-to-CR3 insns, not anywhere else, in
particular not when loading nested guest state.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Paul Durrant <paul@xxxxxxx>
---
v3: Further restrict "noflush" local variable scopes. Remove (now
    redundant) zapping of X86_CR3_NOFLUSH from hvm_monitor_cr().

---
 xen/arch/x86/hvm/emulate.c        |    8 +++++++-
 xen/arch/x86/hvm/hvm.c            |   20 ++++++++++----------
 xen/arch/x86/hvm/monitor.c        |    3 ---
 xen/arch/x86/hvm/svm/nestedsvm.c  |    6 +++---
 xen/arch/x86/hvm/vm_event.c       |    2 +-
 xen/arch/x86/hvm/vmx/vvmx.c       |    4 ++--
 xen/include/asm-x86/domain.h      |    2 ++
 xen/include/asm-x86/hvm/support.h |    2 +-
 8 files changed, 26 insertions(+), 21 deletions(-)

--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -2123,8 +2123,14 @@ static int hvmemul_write_cr(
         break;
 
     case 3:
-        rc = hvm_set_cr3(val, true);
+    {
+        bool noflush = hvm_pcid_enabled(current) && (val & X86_CR3_NOFLUSH);
+
+        if ( noflush )
+            val &= ~X86_CR3_NOFLUSH;
+        rc = hvm_set_cr3(val, noflush, true);
         break;
+    }
 
     case 4:
         rc = hvm_set_cr4(val, true);
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2076,8 +2076,14 @@ int hvm_mov_to_cr(unsigned int cr, unsig
         break;
 
     case 3:
-        rc = hvm_set_cr3(val, true);
+    {
+        bool noflush = hvm_pcid_enabled(curr) && (val & X86_CR3_NOFLUSH);
+
+        if ( noflush )
+            val &= ~X86_CR3_NOFLUSH;
+        rc = hvm_set_cr3(val, noflush, true);
         break;
+    }
 
     case 4:
         rc = hvm_set_cr4(val, true);
@@ -2294,12 +2300,11 @@ int hvm_set_cr0(unsigned long value, boo
     return X86EMUL_OKAY;
 }
 
-int hvm_set_cr3(unsigned long value, bool may_defer)
+int hvm_set_cr3(unsigned long value, bool noflush, bool may_defer)
 {
     struct vcpu *v = current;
     struct page_info *page;
     unsigned long old = v->arch.hvm.guest_cr[3];
-    bool noflush = false;
 
     if ( may_defer && unlikely(v->domain->arch.monitor.write_ctrlreg_enabled &
                                monitor_ctrlreg_bitmask(VM_EVENT_X86_CR3)) )
@@ -2311,17 +2316,12 @@ int hvm_set_cr3(unsigned long value, boo
             /* The actual write will occur in hvm_do_resume(), if permitted. */
             v->arch.vm_event->write_data.do_write.cr3 = 1;
             v->arch.vm_event->write_data.cr3 = value;
+            v->arch.vm_event->write_data.cr3_noflush = noflush;
 
             return X86EMUL_OKAY;
         }
     }
 
-    if ( hvm_pcid_enabled(v) ) /* Clear the noflush bit. */
-    {
-        noflush = value & X86_CR3_NOFLUSH;
-        value &= ~X86_CR3_NOFLUSH;
-    }
-
     if ( hvm_paging_enabled(v) && !paging_mode_hap(v->domain) &&
          ((value ^ v->arch.hvm.guest_cr[3]) >> PAGE_SHIFT) )
     {
@@ -3016,7 +3016,7 @@ void hvm_task_switch(
     if ( task_switch_load_seg(x86_seg_ldtr, tss.ldt, new_cpl, 0) )
         goto out;
 
-    rc = hvm_set_cr3(tss.cr3, true);
+    rc = hvm_set_cr3(tss.cr3, false, true);
     if ( rc == X86EMUL_EXCEPTION )
         hvm_inject_hw_exception(TRAP_gp_fault, 0);
     if ( rc != X86EMUL_OKAY )
--- a/xen/arch/x86/hvm/monitor.c
+++ b/xen/arch/x86/hvm/monitor.c
@@ -38,9 +38,6 @@ bool hvm_monitor_cr(unsigned int index,
     struct arch_domain *ad = &curr->domain->arch;
     unsigned int ctrlreg_bitmask = monitor_ctrlreg_bitmask(index);
 
-    if ( index == VM_EVENT_X86_CR3 && hvm_pcid_enabled(curr) )
-        value &= ~X86_CR3_NOFLUSH; /* Clear the noflush bit. */
-
     if ( (ad->monitor.write_ctrlreg_enabled & ctrlreg_bitmask) &&
          (!(ad->monitor.write_ctrlreg_onchangeonly & ctrlreg_bitmask) ||
           value != old) &&
--- a/xen/arch/x86/hvm/svm/nestedsvm.c
+++ b/xen/arch/x86/hvm/svm/nestedsvm.c
@@ -324,7 +324,7 @@ static int nsvm_vcpu_hostrestore(struct
         v->arch.guest_table = pagetable_null();
         /* hvm_set_cr3() below sets v->arch.hvm.guest_cr[3] for us. */
     }
-    rc = hvm_set_cr3(n1vmcb->_cr3, true);
+    rc = hvm_set_cr3(n1vmcb->_cr3, false, true);
     if ( rc == X86EMUL_EXCEPTION )
         hvm_inject_hw_exception(TRAP_gp_fault, 0);
     if (rc != X86EMUL_OKAY)
@@ -584,7 +584,7 @@ static int nsvm_vmcb_prepare4vmrun(struc
         nestedsvm_vmcb_set_nestedp2m(v, ns_vmcb, n2vmcb);
 
         /* hvm_set_cr3() below sets v->arch.hvm.guest_cr[3] for us. */
-        rc = hvm_set_cr3(ns_vmcb->_cr3, true);
+        rc = hvm_set_cr3(ns_vmcb->_cr3, false, true);
         if ( rc == X86EMUL_EXCEPTION )
             hvm_inject_hw_exception(TRAP_gp_fault, 0);
         if (rc != X86EMUL_OKAY)
@@ -598,7 +598,7 @@ static int nsvm_vmcb_prepare4vmrun(struc
          * we assume it intercepts page faults.
          */
         /* hvm_set_cr3() below sets v->arch.hvm.guest_cr[3] for us. */
-        rc = hvm_set_cr3(ns_vmcb->_cr3, true);
+        rc = hvm_set_cr3(ns_vmcb->_cr3, false, true);
         if ( rc == X86EMUL_EXCEPTION )
             hvm_inject_hw_exception(TRAP_gp_fault, 0);
         if (rc != X86EMUL_OKAY)
--- a/xen/arch/x86/hvm/vm_event.c
+++ b/xen/arch/x86/hvm/vm_event.c
@@ -110,7 +110,7 @@ void hvm_vm_event_do_resume(struct vcpu
 
     if ( unlikely(w->do_write.cr3) )
     {
-        if ( hvm_set_cr3(w->cr3, false) == X86EMUL_EXCEPTION )
+        if ( hvm_set_cr3(w->cr3, w->cr3_noflush, false) == X86EMUL_EXCEPTION )
             hvm_inject_hw_exception(TRAP_gp_fault, 0);
 
         w->do_write.cr3 = 0;
--- a/xen/arch/x86/hvm/vmx/vvmx.c
+++ b/xen/arch/x86/hvm/vmx/vvmx.c
@@ -1032,7 +1032,7 @@ static void load_shadow_guest_state(stru
     if ( rc == X86EMUL_EXCEPTION )
         hvm_inject_hw_exception(TRAP_gp_fault, 0);
 
-    rc = hvm_set_cr3(get_vvmcs(v, GUEST_CR3), true);
+    rc = hvm_set_cr3(get_vvmcs(v, GUEST_CR3), false, true);
     if ( rc == X86EMUL_EXCEPTION )
         hvm_inject_hw_exception(TRAP_gp_fault, 0);
 
@@ -1246,7 +1246,7 @@ static void load_vvmcs_host_state(struct
     if ( rc == X86EMUL_EXCEPTION )
         hvm_inject_hw_exception(TRAP_gp_fault, 0);
 
-    rc = hvm_set_cr3(get_vvmcs(v, HOST_CR3), true);
+    rc = hvm_set_cr3(get_vvmcs(v, HOST_CR3), false, true);
     if ( rc == X86EMUL_EXCEPTION )
         hvm_inject_hw_exception(TRAP_gp_fault, 0);
 
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -274,6 +274,8 @@ struct monitor_write_data {
         unsigned int cr4 : 1;
     } do_write;
 
+    bool cr3_noflush;
+
     uint32_t msr;
     uint64_t value;
     uint64_t cr0;
--- a/xen/include/asm-x86/hvm/support.h
+++ b/xen/include/asm-x86/hvm/support.h
@@ -136,7 +136,7 @@ void hvm_shadow_handle_cd(struct vcpu *v
  */
 int hvm_set_efer(uint64_t value);
 int hvm_set_cr0(unsigned long value, bool may_defer);
-int hvm_set_cr3(unsigned long value, bool may_defer);
+int hvm_set_cr3(unsigned long value, bool noflush, bool may_defer);
 int hvm_set_cr4(unsigned long value, bool may_defer);
 int hvm_descriptor_access_intercept(uint64_t exit_info,
                                     uint64_t vmx_exit_qualification,


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