[PATCH v2 2/7] x86/vm-event/monitor: relocate code-motion more appropriately

[Corneliu ZUZU <czuzu@bitdefender.com>]

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).

* Separate enabling/disabling of CPU_BASED_CR3_LOAD_EXITING for CR3 monitor
vm-events from CR0 node @ vmx_update_guest_cr(v, 0) into newly added function
vmx_vm_event_update_cr3_traps(d); also, for a better interface, create generic
function write_ctrlreg_adjust_traps (in x86/monitor.c) which deals with setting
up any traps for cr-write monitor vm-events.

Signed-off-by: Corneliu ZUZU <czuzu@bitdefender.com>
Acked-by: Razvan Cojocaru <rcojocaru@bitdefender.com>
---
Changed since v1:
  * separated vmx-specific code motion in vmx_vm_event_update_cr3_traps
  * minor: reorder added include alphabetically
  * minor: move arch_monitor_write_data call in if @ hvm_do_resume
---
 xen/arch/x86/hvm/hvm.c            | 46 ++++++++++++-------------------
 xen/arch/x86/hvm/vmx/vmx.c        | 58 +++++++++++++++++++++++++++++++++++----
 xen/arch/x86/monitor.c            | 48 +++++++++++++++++++++++++++-----
 xen/include/asm-x86/hvm/vmx/vmx.h |  1 +
 xen/include/asm-x86/monitor.h     |  2 ++
 5 files changed, 114 insertions(+), 41 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index c89ab6e..e3829d2 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;
@@ -494,29 +492,7 @@ 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 */
@@ -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 8ab074f..0fa3fea 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);
         }
@@ -3899,6 +3894,59 @@ void vmx_vmenter_helper(const struct cpu_user_regs *regs)
 }
 
 /*
+ * Adjusts domain CR3 load-exiting execution control for CR3-write monitor
+ * vm-event.
+ */
+void vmx_vm_event_update_cr3_traps(struct domain *d)
+{
+    struct vcpu *v;
+    struct arch_vmx_struct *avmx;
+    unsigned int cr3_bitmask;
+    bool_t cr3_vmevent, cr3_ldexit;
+
+    /* domain must be paused */
+    ASSERT(atomic_read(&d->pause_count));
+
+    /* non-hap domains trap CR3 writes unconditionally */
+    if ( !paging_mode_hap(d) )
+    {
+#ifndef NDEBUG
+        for_each_vcpu ( d, v )
+            ASSERT(v->arch.hvm_vmx.exec_control & CPU_BASED_CR3_LOAD_EXITING);
+#endif
+        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);
+    }
+}
+
+/*
  * Local variables:
  * mode: C
  * c-file-style: "BSD"
diff --git a/xen/arch/x86/monitor.c b/xen/arch/x86/monitor.c
index 205df41..2bb7d86 100644
--- a/xen/arch/x86/monitor.c
+++ b/xen/arch/x86/monitor.c
@@ -19,7 +19,9 @@
  * License along with this program; If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <asm/hvm/vmx/vmx.h>
 #include <asm/monitor.h>
+#include <asm/vm_event.h>
 #include <public/vm_event.h>
 
 int arch_monitor_init_domain(struct domain *d)
@@ -41,6 +43,35 @@ 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 = &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 +150,15 @@ bool_t monitored_msr(const struct domain *d, u32 msr)
     return test_bit(msr, bitmap);
 }
 
+static inline void write_ctrlreg_adjust_traps(struct domain *d, uint8_t index)
+{
+    /* vmx only */
+    ASSERT(cpu_has_vmx);
+
+    if ( VM_EVENT_X86_CR3 == index )
+        vmx_vm_event_update_cr3_traps(d);
+}
+
 int arch_monitor_domctl_event(struct domain *d,
                               struct xen_domctl_monitor_op *mop)
 {
@@ -159,13 +199,7 @@ 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, mop->u.mov_to_cr.index);
 
         domain_unpause(d);
 
diff --git a/xen/include/asm-x86/hvm/vmx/vmx.h b/xen/include/asm-x86/hvm/vmx/vmx.h
index 359b2a9..15bb592 100644
--- a/xen/include/asm-x86/hvm/vmx/vmx.h
+++ b/xen/include/asm-x86/hvm/vmx/vmx.h
@@ -101,6 +101,7 @@ void vmx_update_debug_state(struct vcpu *v);
 void vmx_update_exception_bitmap(struct vcpu *v);
 void vmx_update_cpu_exec_control(struct vcpu *v);
 void vmx_update_secondary_exec_control(struct vcpu *v);
+void vmx_vm_event_update_cr3_traps(struct domain *d);
 
 #define POSTED_INTR_ON  0
 #define POSTED_INTR_SN  1
diff --git a/xen/include/asm-x86/monitor.h b/xen/include/asm-x86/monitor.h
index a9db3c0..0611681 100644
--- a/xen/include/asm-x86/monitor.h
+++ b/xen/include/asm-x86/monitor.h
@@ -94,6 +94,8 @@ 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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