[PATCH 4/7] vm-event/x86: use vm_event_vcpu_enter properly

[Corneliu ZUZU <czuzu@bitdefender.com>]

After introducing vm_event_vcpu_enter, it makes sense to move the following
code there:
- handling of monitor_write_data from hvm_do_resume
- enabling/disabling CPU_BASED_CR3_LOAD_EXITING from vmx_update_guest_cr(v, 0)

Signed-off-by: Corneliu ZUZU <czuzu@bitdefender.com>
---
 xen/arch/x86/hvm/hvm.c         |  62 +++++--------------------
 xen/arch/x86/hvm/vmx/vmx.c     |  12 ++---
 xen/arch/x86/monitor.c         |   9 ----
 xen/arch/x86/vm_event.c        | 102 +++++++++++++++++++++++++++++++++++++++++
 xen/include/asm-x86/vm_event.h |   5 +-
 5 files changed, 119 insertions(+), 71 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 770bb50..2f48846 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -462,52 +462,6 @@ void hvm_do_resume(struct vcpu *v)
     if ( !handle_hvm_io_completion(v) )
         return;
 
-    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;
-
-            if ( v->arch.vm_event->emulate_flags &
-                 VM_EVENT_FLAG_SET_EMUL_READ_DATA )
-                kind = EMUL_KIND_SET_CONTEXT;
-            else if ( v->arch.vm_event->emulate_flags &
-                      VM_EVENT_FLAG_EMULATE_NOWRITE )
-                kind = EMUL_KIND_NOWRITE;
-
-            hvm_mem_access_emulate_one(kind, TRAP_invalid_op,
-                                       HVM_DELIVER_NO_ERROR_CODE);
-
-            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;
-        }
-    }
-
     vm_event_vcpu_enter(v);
 
     /* Inject pending hw/sw trap */
@@ -2199,7 +2153,9 @@ int hvm_set_cr0(unsigned long value, bool_t may_defer)
 
         if ( hvm_event_crX(CR0, value, old_value) )
         {
-            /* The actual write will occur in hvm_do_resume(), if permitted. */
+            /* The actual write will occur in vcpu_enter_write_data(), if
+             * permitted.
+             */
             v->arch.vm_event->write_data.do_write.cr0 = 1;
             v->arch.vm_event->write_data.cr0 = value;
 
@@ -2301,7 +2257,9 @@ int hvm_set_cr3(unsigned long value, bool_t may_defer)
 
         if ( hvm_event_crX(CR3, value, old) )
         {
-            /* The actual write will occur in hvm_do_resume(), if permitted. */
+            /* The actual write will occur in vcpu_enter_write_data(), if
+             * permitted.
+             */
             v->arch.vm_event->write_data.do_write.cr3 = 1;
             v->arch.vm_event->write_data.cr3 = value;
 
@@ -2381,7 +2339,9 @@ int hvm_set_cr4(unsigned long value, bool_t may_defer)
 
         if ( hvm_event_crX(CR4, value, old_cr) )
         {
-            /* The actual write will occur in hvm_do_resume(), if permitted. */
+            /* The actual write will occur in vcpu_enter_write_data(), if
+             * permitted.
+             */
             v->arch.vm_event->write_data.do_write.cr4 = 1;
             v->arch.vm_event->write_data.cr4 = value;
 
@@ -3761,7 +3721,9 @@ 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 vcpu_enter_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 b43b94a..8b76ef9 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -35,7 +35,6 @@
 #include <asm/guest_access.h>
 #include <asm/debugreg.h>
 #include <asm/msr.h>
-#include <asm/paging.h>
 #include <asm/p2m.h>
 #include <asm/mem_sharing.h>
 #include <asm/hvm/emulate.h>
@@ -58,7 +57,6 @@
 #include <asm/hvm/nestedhvm.h>
 #include <asm/altp2m.h>
 #include <asm/event.h>
-#include <asm/monitor.h>
 #include <public/arch-x86/cpuid.h>
 
 static bool_t __initdata opt_force_ept;
@@ -1432,18 +1430,16 @@ static void vmx_update_guest_cr(struct vcpu *v, unsigned int cr)
         if ( paging_mode_hap(v->domain) )
         {
             /* Manage GUEST_CR3 when CR0.PE=0. */
+            uint32_t old_ctls = v->arch.hvm_vmx.exec_control;
             uint32_t cr3_ctls = (CPU_BASED_CR3_LOAD_EXITING |
                                  CPU_BASED_CR3_STORE_EXITING);
+
             v->arch.hvm_vmx.exec_control &= ~cr3_ctls;
             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;
-
-            vmx_update_cpu_exec_control(v);
+            if ( old_ctls != v->arch.hvm_vmx.exec_control )
+                vmx_update_cpu_exec_control(v);
         }
 
         if ( !nestedhvm_vcpu_in_guestmode(v) )
diff --git a/xen/arch/x86/monitor.c b/xen/arch/x86/monitor.c
index 1fec412..1e5445f 100644
--- a/xen/arch/x86/monitor.c
+++ b/xen/arch/x86/monitor.c
@@ -20,7 +20,6 @@
  */
 
 #include <asm/monitor.h>
-#include <public/vm_event.h>
 
 int arch_monitor_domctl_event(struct domain *d,
                               struct xen_domctl_monitor_op *mop)
@@ -62,14 +61,6 @@ 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);
-        }
-
         domain_unpause(d);
 
         break;
diff --git a/xen/arch/x86/vm_event.c b/xen/arch/x86/vm_event.c
index f7eb24a..94b50fc 100644
--- a/xen/arch/x86/vm_event.c
+++ b/xen/arch/x86/vm_event.c
@@ -19,6 +19,9 @@
  */
 
 #include <xen/vm_event.h>
+#include <asm/monitor.h>
+#include <asm/paging.h>
+#include <asm/hvm/vmx/vmx.h>
 
 /* Implicitly serialized by the domctl lock. */
 int vm_event_init_domain(struct domain *d)
@@ -179,6 +182,105 @@ void vm_event_fill_regs(vm_event_request_t *req)
     req->data.regs.x86.cs_arbytes = seg.attr.bytes;
 }
 
+static inline void vcpu_enter_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 ( unlikely(v->arch.vm_event->emulate_flags) )
+    {
+        enum emul_kind kind = EMUL_KIND_NORMAL;
+
+        if ( v->arch.vm_event->emulate_flags &
+             VM_EVENT_FLAG_SET_EMUL_READ_DATA )
+            kind = EMUL_KIND_SET_CONTEXT;
+        else if ( v->arch.vm_event->emulate_flags &
+                  VM_EVENT_FLAG_EMULATE_NOWRITE )
+            kind = EMUL_KIND_NOWRITE;
+
+        hvm_mem_access_emulate_one(kind, TRAP_invalid_op,
+                                   HVM_DELIVER_NO_ERROR_CODE);
+
+        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;
+    }
+}
+
+static inline void vcpu_enter_adjust_traps(struct vcpu *v)
+{
+    struct domain *d = v->domain;
+    struct arch_vmx_struct *avmx = &v->arch.hvm_vmx;
+    bool_t cr3_ldexit, cr3_vmevent;
+    unsigned int cr3_bitmask;
+
+    /* Adjust CR3 load-exiting (for monitor vm-events). */
+
+    cr3_bitmask = monitor_ctrlreg_bitmask(VM_EVENT_X86_CR3);
+    cr3_vmevent = !!(d->arch.monitor.write_ctrlreg_enabled & cr3_bitmask);
+    cr3_ldexit = !!(avmx->exec_control & CPU_BASED_CR3_LOAD_EXITING);
+
+    if ( likely(cr3_vmevent == cr3_ldexit) )
+        return;
+
+    if ( !paging_mode_hap(d) )
+    {
+        /* non-hap domains trap CR3 writes unconditionally */
+        ASSERT(cr3_ldexit);
+        return;
+    }
+
+    /*
+     * 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) )
+        return;
+
+    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);
+}
+
+void arch_vm_event_vcpu_enter(struct vcpu *v)
+{
+    /* vmx only */
+    ASSERT( cpu_has_vmx );
+    vcpu_enter_write_data(v);
+    vcpu_enter_adjust_traps(v);
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/include/asm-x86/vm_event.h b/xen/include/asm-x86/vm_event.h
index 6fb3b58..c4b5def 100644
--- a/xen/include/asm-x86/vm_event.h
+++ b/xen/include/asm-x86/vm_event.h
@@ -43,10 +43,7 @@ void vm_event_set_registers(struct vcpu *v, vm_event_response_t *rsp);
 
 void vm_event_fill_regs(vm_event_request_t *req);
 
-static inline void arch_vm_event_vcpu_enter(struct vcpu *v)
-{
-    /* Nothing to do. */
-}
+void arch_vm_event_vcpu_enter(struct vcpu *v);
 
 /*
  * Monitor vm-events.
-- 
2.5.0


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