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[Xen-devel] [PATCH 3/8] x86/vm-event/monitor: relocate code-motion more appropriately



For readability:

* Add function arch_monitor_write_data (in x86/monitor.c) and separate handling
of monitor_write_data there (previously done directly in hvm_do_resume).

* Add function write_ctrlreg_adjust_traps (in x86/monitor.c) and relocate
enabling/disabling of CPU_BASED_CR3_LOAD_EXITING for CR3 monitor vm-events there
(previously done through CR0 node @ vmx_update_guest_cr(v, 0)).

Signed-off-by: Corneliu ZUZU <czuzu@xxxxxxxxxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c        | 48 +++++++++-------------
 xen/arch/x86/hvm/vmx/vmx.c    |  5 ---
 xen/arch/x86/monitor.c        | 94 +++++++++++++++++++++++++++++++++++++++----
 xen/include/asm-x86/monitor.h |  2 +
 4 files changed, 107 insertions(+), 42 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index c89ab6e..5481a6e 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -475,8 +475,6 @@ void hvm_do_resume(struct vcpu *v)
 
     if ( unlikely(v->arch.vm_event) )
     {
-        struct monitor_write_data *w = &v->arch.vm_event->write_data;
-
         if ( v->arch.vm_event->emulate_flags )
         {
             enum emul_kind kind = EMUL_KIND_NORMAL;
@@ -493,32 +491,10 @@ void hvm_do_resume(struct vcpu *v)
 
             v->arch.vm_event->emulate_flags = 0;
         }
-
-        if ( w->do_write.msr )
-        {
-            hvm_msr_write_intercept(w->msr, w->value, 0);
-            w->do_write.msr = 0;
-        }
-
-        if ( w->do_write.cr0 )
-        {
-            hvm_set_cr0(w->cr0, 0);
-            w->do_write.cr0 = 0;
-        }
-
-        if ( w->do_write.cr4 )
-        {
-            hvm_set_cr4(w->cr4, 0);
-            w->do_write.cr4 = 0;
-        }
-
-        if ( w->do_write.cr3 )
-        {
-            hvm_set_cr3(w->cr3, 0);
-            w->do_write.cr3 = 0;
-        }
     }
 
+    arch_monitor_write_data(v);
+
     /* Inject pending hw/sw trap */
     if ( v->arch.hvm_vcpu.inject_trap.vector != -1 )
     {
@@ -2206,7 +2182,10 @@ int hvm_set_cr0(unsigned long value, bool_t may_defer)
 
         if ( hvm_monitor_crX(CR0, value, old_value) )
         {
-            /* The actual write will occur in hvm_do_resume(), if permitted. */
+            /*
+             * The actual write will occur in arch_monitor_write_data(), if
+             * permitted.
+             */
             v->arch.vm_event->write_data.do_write.cr0 = 1;
             v->arch.vm_event->write_data.cr0 = value;
 
@@ -2308,7 +2287,10 @@ int hvm_set_cr3(unsigned long value, bool_t may_defer)
 
         if ( hvm_monitor_crX(CR3, value, old) )
         {
-            /* The actual write will occur in hvm_do_resume(), if permitted. */
+            /*
+             * The actual write will occur in arch_monitor_write_data(), if
+             * permitted.
+             */
             v->arch.vm_event->write_data.do_write.cr3 = 1;
             v->arch.vm_event->write_data.cr3 = value;
 
@@ -2388,7 +2370,10 @@ int hvm_set_cr4(unsigned long value, bool_t may_defer)
 
         if ( hvm_monitor_crX(CR4, value, old_cr) )
         {
-            /* The actual write will occur in hvm_do_resume(), if permitted. */
+            /*
+             * The actual write will occur in arch_monitor_write_data(), if
+             * permitted.
+             */
             v->arch.vm_event->write_data.do_write.cr4 = 1;
             v->arch.vm_event->write_data.cr4 = value;
 
@@ -3767,7 +3752,10 @@ int hvm_msr_write_intercept(unsigned int msr, uint64_t 
msr_content,
     {
         ASSERT(v->arch.vm_event);
 
-        /* The actual write will occur in hvm_do_resume() (if permitted). */
+        /*
+         * The actual write will occur in arch_monitor_write_data(), if
+         * permitted.
+         */
         v->arch.vm_event->write_data.do_write.msr = 1;
         v->arch.vm_event->write_data.msr = msr;
         v->arch.vm_event->write_data.value = msr_content;
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 15c84c2..de04e6c 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -1442,11 +1442,6 @@ static void vmx_update_guest_cr(struct vcpu *v, unsigned 
int cr)
             if ( !hvm_paging_enabled(v) && !vmx_unrestricted_guest(v) )
                 v->arch.hvm_vmx.exec_control |= cr3_ctls;
 
-            /* Trap CR3 updates if CR3 memory events are enabled. */
-            if ( v->domain->arch.monitor.write_ctrlreg_enabled &
-                 monitor_ctrlreg_bitmask(VM_EVENT_X86_CR3) )
-                v->arch.hvm_vmx.exec_control |= CPU_BASED_CR3_LOAD_EXITING;
-
             if ( old_ctls != v->arch.hvm_vmx.exec_control )
                 vmx_update_cpu_exec_control(v);
         }
diff --git a/xen/arch/x86/monitor.c b/xen/arch/x86/monitor.c
index a271161..90e4856 100644
--- a/xen/arch/x86/monitor.c
+++ b/xen/arch/x86/monitor.c
@@ -20,6 +20,9 @@
  */
 
 #include <asm/monitor.h>
+#include <asm/paging.h>
+#include <asm/hvm/vmx/vmx.h>
+#include <asm/vm_event.h>
 #include <public/vm_event.h>
 
 int arch_monitor_init_domain(struct domain *d)
@@ -41,6 +44,40 @@ void arch_monitor_cleanup_domain(struct domain *d)
     memset(&d->monitor, 0, sizeof(d->monitor));
 }
 
+void arch_monitor_write_data(struct vcpu *v)
+{
+    struct monitor_write_data *w;
+
+    if ( likely(!v->arch.vm_event) )
+        return;
+
+    w = &v->arch.vm_event->write_data;
+
+    if ( w->do_write.msr )
+    {
+        hvm_msr_write_intercept(w->msr, w->value, 0);
+        w->do_write.msr = 0;
+    }
+
+    if ( w->do_write.cr0 )
+    {
+        hvm_set_cr0(w->cr0, 0);
+        w->do_write.cr0 = 0;
+    }
+
+    if ( w->do_write.cr4 )
+    {
+        hvm_set_cr4(w->cr4, 0);
+        w->do_write.cr4 = 0;
+    }
+
+    if ( w->do_write.cr3 )
+    {
+        hvm_set_cr3(w->cr3, 0);
+        w->do_write.cr3 = 0;
+    }
+}
+
 static unsigned long *monitor_bitmap_for_msr(const struct domain *d, u32 *msr)
 {
     ASSERT(d->arch.monitor.msr_bitmap && msr);
@@ -119,6 +156,55 @@ bool_t monitored_msr(const struct domain *d, u32 msr)
     return test_bit(msr, bitmap);
 }
 
+static void write_ctrlreg_adjust_traps(struct domain *d)
+{
+    struct vcpu *v;
+    struct arch_vmx_struct *avmx;
+    unsigned int cr3_bitmask;
+    bool_t cr3_vmevent, cr3_ldexit;
+
+    /* Adjust CR3 load-exiting. */
+
+    /* vmx only */
+    ASSERT(cpu_has_vmx);
+
+    /* non-hap domains trap CR3 writes unconditionally */
+    if ( !paging_mode_hap(d) )
+    {
+        for_each_vcpu ( d, v )
+            ASSERT(v->arch.hvm_vmx.exec_control & CPU_BASED_CR3_LOAD_EXITING);
+        return;
+    }
+
+    cr3_bitmask = monitor_ctrlreg_bitmask(VM_EVENT_X86_CR3);
+    cr3_vmevent = !!(d->arch.monitor.write_ctrlreg_enabled & cr3_bitmask);
+
+    for_each_vcpu ( d, v )
+    {
+        avmx = &v->arch.hvm_vmx;
+        cr3_ldexit = !!(avmx->exec_control & CPU_BASED_CR3_LOAD_EXITING);
+
+        if ( cr3_vmevent == cr3_ldexit )
+            continue;
+
+        /*
+         * If CR0.PE=0, CR3 load exiting must remain enabled.
+         * See vmx_update_guest_cr code motion for cr = 0.
+         */
+        if ( cr3_ldexit && !hvm_paging_enabled(v) && 
!vmx_unrestricted_guest(v) )
+            continue;
+
+        if ( cr3_vmevent )
+            avmx->exec_control |= CPU_BASED_CR3_LOAD_EXITING;
+        else
+            avmx->exec_control &= ~CPU_BASED_CR3_LOAD_EXITING;
+
+        vmx_vmcs_enter(v);
+        vmx_update_cpu_exec_control(v);
+        vmx_vmcs_exit(v);
+    }
+}
+
 int arch_monitor_domctl_event(struct domain *d,
                               struct xen_domctl_monitor_op *mop)
 {
@@ -159,13 +245,7 @@ int arch_monitor_domctl_event(struct domain *d,
         else
             ad->monitor.write_ctrlreg_enabled &= ~ctrlreg_bitmask;
 
-        if ( VM_EVENT_X86_CR3 == mop->u.mov_to_cr.index )
-        {
-            struct vcpu *v;
-            /* Latches new CR3 mask through CR0 code. */
-            for_each_vcpu ( d, v )
-                hvm_update_guest_cr(v, 0);
-        }
+        write_ctrlreg_adjust_traps(d);
 
         domain_unpause(d);
 
diff --git a/xen/include/asm-x86/monitor.h b/xen/include/asm-x86/monitor.h
index 94b6768..1068376 100644
--- a/xen/include/asm-x86/monitor.h
+++ b/xen/include/asm-x86/monitor.h
@@ -93,6 +93,8 @@ int arch_monitor_init_domain(struct domain *d);
 
 void arch_monitor_cleanup_domain(struct domain *d);
 
+void arch_monitor_write_data(struct vcpu *v);
+
 bool_t monitored_msr(const struct domain *d, u32 msr);
 
 #endif /* __ASM_X86_MONITOR_H__ */
-- 
2.5.0


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