[PATCH v3 2/2] xen/vm-events: Move parts of monitor_domctl code to common-side.

[Corneliu ZUZU <czuzu@bitdefender.com>]

This patch moves monitor_domctl to common-side.
Purpose: move what's common to common, prepare for implementation
of such vm-events on ARM.

* move get_capabilities to arch-side => arch_monitor_get_capabilities.
* add arch-side monitor op handling function => arch_monitor_domctl_op.
  e.g. X86-side handles XEN_DOMCTL_MONITOR_OP_EMULATE_EACH_REP op
* add arch-side monitor event handling function => arch_monitor_domctl_event.
  e.g. X86-side handles XEN_DOMCTL_MONITOR_EVENT_MOV_TO_MSR event enable/disable
* remove status_check

Signed-off-by: Corneliu ZUZU <czuzu@bitdefender.com>
---
 MAINTAINERS                   |   1 +
 xen/arch/x86/monitor.c        | 158 ++++++++++++------------------------------
 xen/common/Makefile           |   1 +
 xen/common/domctl.c           |   2 +-
 xen/common/monitor.c          |  69 ++++++++++++++++++
 xen/include/asm-arm/monitor.h |  34 +++++++--
 xen/include/asm-x86/monitor.h |  53 ++++++++++++--
 xen/include/xen/monitor.h     |  30 ++++++++
 8 files changed, 226 insertions(+), 122 deletions(-)
 create mode 100644 xen/common/monitor.c
 create mode 100644 xen/include/xen/monitor.h

diff --git a/MAINTAINERS b/MAINTAINERS
index f07384c..5cbb1dc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -355,6 +355,7 @@ M:	Tamas K Lengyel <tamas@tklengyel.com>
 S:	Supported
 F:	xen/common/vm_event.c
 F:	xen/common/mem_access.c
+F:	xen/common/monitor.c
 F:	xen/arch/x86/hvm/event.c
 F:	xen/arch/x86/monitor.c
 F:	xen/arch/*/vm_event.c
diff --git a/xen/arch/x86/monitor.c b/xen/arch/x86/monitor.c
index 1d43880..069c3c7 100644
--- a/xen/arch/x86/monitor.c
+++ b/xen/arch/x86/monitor.c
@@ -1,9 +1,10 @@
 /*
  * arch/x86/monitor.c
  *
- * Architecture-specific monitor_op domctl handler.
+ * Arch-specific monitor_op domctl handler.
  *
  * Copyright (c) 2015 Tamas K Lengyel (tamas@tklengyel.com)
+ * Copyright (c) 2016, Bitdefender S.R.L.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public
@@ -18,87 +19,14 @@
  * License along with this program; If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <xen/config.h>
-#include <xen/sched.h>
-#include <xen/mm.h>
-#include <asm/domain.h>
 #include <asm/monitor.h>
-#include <public/domctl.h>
-#include <xsm/xsm.h>
+#include <public/vm_event.h>
 
-/*
- * Sanity check whether option is already enabled/disabled
- */
-static inline
-int status_check(struct xen_domctl_monitor_op *mop, bool_t status)
-{
-    bool_t requested_status = (mop->op == XEN_DOMCTL_MONITOR_OP_ENABLE);
-
-    if ( status == requested_status )
-        return -EEXIST;
-
-    return 0;
-}
-
-static inline uint32_t get_capabilities(struct domain *d)
-{
-    uint32_t capabilities = 0;
-
-    /*
-     * At the moment only Intel HVM domains are supported. However, event
-     * delivery could be extended to AMD and PV domains.
-     */
-    if ( !is_hvm_domain(d) || !cpu_has_vmx )
-        return capabilities;
-
-    capabilities = (1 << XEN_DOMCTL_MONITOR_EVENT_WRITE_CTRLREG) |
-                   (1 << XEN_DOMCTL_MONITOR_EVENT_MOV_TO_MSR) |
-                   (1 << XEN_DOMCTL_MONITOR_EVENT_SOFTWARE_BREAKPOINT) |
-                   (1 << XEN_DOMCTL_MONITOR_EVENT_GUEST_REQUEST);
-
-    /* Since we know this is on VMX, we can just call the hvm func */
-    if ( hvm_is_singlestep_supported() )
-        capabilities |= (1 << XEN_DOMCTL_MONITOR_EVENT_SINGLESTEP);
-
-    return capabilities;
-}
-
-int monitor_domctl(struct domain *d, struct xen_domctl_monitor_op *mop)
+int arch_monitor_domctl_event(struct domain *d,
+                              struct xen_domctl_monitor_op *mop)
 {
-    int rc;
     struct arch_domain *ad = &d->arch;
-    uint32_t capabilities = get_capabilities(d);
-
-    if ( current->domain == d ) /* no domain_pause() */
-        return -EPERM;
-
-    rc = xsm_vm_event_control(XSM_PRIV, d, mop->op, mop->event);
-    if ( rc )
-        return rc;
-
-    switch ( mop->op )
-    {
-    case XEN_DOMCTL_MONITOR_OP_GET_CAPABILITIES:
-        mop->event = capabilities;
-        return 0;
-
-    case XEN_DOMCTL_MONITOR_OP_EMULATE_EACH_REP:
-        domain_pause(d);
-        ad->mem_access_emulate_each_rep = !!mop->event;
-        domain_unpause(d);
-        return 0;
-    }
-
-    /*
-     * Sanity check
-     */
-    if ( mop->op != XEN_DOMCTL_MONITOR_OP_ENABLE &&
-         mop->op != XEN_DOMCTL_MONITOR_OP_DISABLE )
-        return -EOPNOTSUPP;
-
-    /* Check if event type is available. */
-    if ( !(capabilities & (1 << mop->event)) )
-        return -EOPNOTSUPP;
+    bool_t requested_status = (XEN_DOMCTL_MONITOR_OP_ENABLE == mop->op);
 
     switch ( mop->event )
     {
@@ -106,13 +34,11 @@ int monitor_domctl(struct domain *d, struct xen_domctl_monitor_op *mop)
     {
         unsigned int ctrlreg_bitmask =
             monitor_ctrlreg_bitmask(mop->u.mov_to_cr.index);
-        bool_t status =
+        bool_t old_status =
             !!(ad->monitor.write_ctrlreg_enabled & ctrlreg_bitmask);
-        struct vcpu *v;
 
-        rc = status_check(mop, status);
-        if ( rc )
-            return rc;
+        if ( unlikely(old_status == requested_status) )
+            return -EEXIST;
 
         domain_pause(d);
 
@@ -126,15 +52,18 @@ int monitor_domctl(struct domain *d, struct xen_domctl_monitor_op *mop)
         else
             ad->monitor.write_ctrlreg_onchangeonly &= ~ctrlreg_bitmask;
 
-        if ( !status )
+        if ( !old_status )
             ad->monitor.write_ctrlreg_enabled |= ctrlreg_bitmask;
         else
             ad->monitor.write_ctrlreg_enabled &= ~ctrlreg_bitmask;
 
-        if ( mop->u.mov_to_cr.index == VM_EVENT_X86_CR3 )
-            /* Latches new CR3 mask through CR0 code */
+        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);
 
@@ -143,77 +72,80 @@ int monitor_domctl(struct domain *d, struct xen_domctl_monitor_op *mop)
 
     case XEN_DOMCTL_MONITOR_EVENT_MOV_TO_MSR:
     {
-        bool_t status = ad->monitor.mov_to_msr_enabled;
+        bool_t old_status = ad->monitor.mov_to_msr_enabled;
 
-        rc = status_check(mop, status);
-        if ( rc )
-            return rc;
+        if ( unlikely(old_status == requested_status) )
+            return -EEXIST;
 
-        if ( mop->op == XEN_DOMCTL_MONITOR_OP_ENABLE &&
-             mop->u.mov_to_msr.extended_capture &&
+        if ( requested_status && mop->u.mov_to_msr.extended_capture &&
              !hvm_enable_msr_exit_interception(d) )
             return -EOPNOTSUPP;
 
         domain_pause(d);
 
-        if ( mop->op == XEN_DOMCTL_MONITOR_OP_ENABLE &&
-             mop->u.mov_to_msr.extended_capture )
-                ad->monitor.mov_to_msr_extended = 1;
+        if ( requested_status && mop->u.mov_to_msr.extended_capture )
+            ad->monitor.mov_to_msr_extended = 1;
         else
             ad->monitor.mov_to_msr_extended = 0;
 
-        ad->monitor.mov_to_msr_enabled = !status;
+        ad->monitor.mov_to_msr_enabled = !old_status;
         domain_unpause(d);
         break;
     }
 
     case XEN_DOMCTL_MONITOR_EVENT_SINGLESTEP:
     {
-        bool_t status = ad->monitor.singlestep_enabled;
+        bool_t old_status = ad->monitor.singlestep_enabled;
 
-        rc = status_check(mop, status);
-        if ( rc )
-            return rc;
+        if ( unlikely(old_status == requested_status) )
+            return -EEXIST;
 
         domain_pause(d);
-        ad->monitor.singlestep_enabled = !status;
+        ad->monitor.singlestep_enabled = !old_status;
         domain_unpause(d);
         break;
     }
 
     case XEN_DOMCTL_MONITOR_EVENT_SOFTWARE_BREAKPOINT:
     {
-        bool_t status = ad->monitor.software_breakpoint_enabled;
+        bool_t old_status = ad->monitor.software_breakpoint_enabled;
 
-        rc = status_check(mop, status);
-        if ( rc )
-            return rc;
+        if ( unlikely(old_status == requested_status) )
+            return -EEXIST;
 
         domain_pause(d);
-        ad->monitor.software_breakpoint_enabled = !status;
+        ad->monitor.software_breakpoint_enabled = !old_status;
         domain_unpause(d);
         break;
     }
 
     case XEN_DOMCTL_MONITOR_EVENT_GUEST_REQUEST:
     {
-        bool_t status = ad->monitor.guest_request_enabled;
+        bool_t old_status = ad->monitor.guest_request_enabled;
 
-        rc = status_check(mop, status);
-        if ( rc )
-            return rc;
+        if ( unlikely(old_status == requested_status) )
+            return -EEXIST;
 
         domain_pause(d);
         ad->monitor.guest_request_sync = mop->u.guest_request.sync;
-        ad->monitor.guest_request_enabled = !status;
+        ad->monitor.guest_request_enabled = !old_status;
         domain_unpause(d);
         break;
     }
 
     default:
-        return -EOPNOTSUPP;
+        /*
+         * Should not be reached unless arch_monitor_get_capabilities() is not
+         * properly implemented. In that case, since reaching this point does
+         * not really break anything, don't crash the hypervisor, issue a
+         * warning instead of BUG().
+         */
+        printk(XENLOG_WARNING
+                "WARNING, BUG: arch_monitor_get_capabilities() not implemented"
+                "properly.\n");
 
-    };
+        return -EOPNOTSUPP;
+    }
 
     return 0;
 }
diff --git a/xen/common/Makefile b/xen/common/Makefile
index 6e82b33..0d76efe 100644
--- a/xen/common/Makefile
+++ b/xen/common/Makefile
@@ -20,6 +20,7 @@ obj-y += lib.o
 obj-y += lzo.o
 obj-$(CONFIG_HAS_MEM_ACCESS) += mem_access.o
 obj-y += memory.o
+obj-y += monitor.o
 obj-y += multicall.o
 obj-y += notifier.o
 obj-y += page_alloc.o
diff --git a/xen/common/domctl.c b/xen/common/domctl.c
index 22fa5d5..b34c0a1 100644
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -25,11 +25,11 @@
 #include <xen/paging.h>
 #include <xen/hypercall.h>
 #include <xen/vm_event.h>
+#include <xen/monitor.h>
 #include <asm/current.h>
 #include <asm/irq.h>
 #include <asm/page.h>
 #include <asm/p2m.h>
-#include <asm/monitor.h>
 #include <public/domctl.h>
 #include <xsm/xsm.h>
 
diff --git a/xen/common/monitor.c b/xen/common/monitor.c
new file mode 100644
index 0000000..b708cab
--- /dev/null
+++ b/xen/common/monitor.c
@@ -0,0 +1,69 @@
+/*
+ * xen/common/monitor.c
+ *
+ * Common monitor_op domctl handler.
+ *
+ * Copyright (c) 2015 Tamas K Lengyel (tamas@tklengyel.com)
+ * Copyright (c) 2016, Bitdefender S.R.L.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <xen/monitor.h>
+#include <xen/sched.h>
+#include <xsm/xsm.h>
+#include <public/domctl.h>
+#include <asm/monitor.h>
+
+int monitor_domctl(struct domain *d, struct xen_domctl_monitor_op *mop)
+{
+    int rc;
+    bool_t requested_status = 0;
+
+    if ( unlikely(current->domain == d) ) /* no domain_pause() */
+        return -EPERM;
+
+    rc = xsm_vm_event_control(XSM_PRIV, d, mop->op, mop->event);
+    if ( unlikely(rc) )
+        return rc;
+
+    switch ( mop->op )
+    {
+    case XEN_DOMCTL_MONITOR_OP_ENABLE:
+        requested_status = 1;
+        /* fallthrough */
+    case XEN_DOMCTL_MONITOR_OP_DISABLE:
+        /* Check if event type is available. */
+        if ( unlikely(!(arch_monitor_get_capabilities(d) & (1 << mop->event))) )
+            return -EOPNOTSUPP;
+        /* Arch-side handles enable/disable ops. */
+        return arch_monitor_domctl_event(d, mop);
+
+    case XEN_DOMCTL_MONITOR_OP_GET_CAPABILITIES:
+        mop->event = arch_monitor_get_capabilities(d);
+        return 0;
+
+    default:
+        /* The monitor op is probably handled on the arch-side. */
+        return arch_monitor_domctl_op(d, mop);
+    }
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/include/asm-arm/monitor.h b/xen/include/asm-arm/monitor.h
index a3a9703..ef7547e 100644
--- a/xen/include/asm-arm/monitor.h
+++ b/xen/include/asm-arm/monitor.h
@@ -1,9 +1,10 @@
 /*
  * include/asm-arm/monitor.h
  *
- * Architecture-specific monitor_op domctl handler.
+ * Arch-specific monitor_op domctl handler.
  *
  * Copyright (c) 2015 Tamas K Lengyel (tamas@tklengyel.com)
+ * Copyright (c) 2016, Bitdefender S.R.L.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public
@@ -24,10 +25,35 @@
 #include <xen/sched.h>
 #include <public/domctl.h>
 
+static inline uint32_t arch_monitor_get_capabilities(struct domain *d)
+{
+    /* No monitor vm-events implemented on ARM. */
+    return 0;
+}
+
+static inline
+int arch_monitor_domctl_op(struct domain *d, struct xen_domctl_monitor_op *mop)
+{
+    /* No arch-specific monitor ops on ARM. */
+    return -EOPNOTSUPP;
+}
+
 static inline
-int monitor_domctl(struct domain *d, struct xen_domctl_monitor_op *op)
+int arch_monitor_domctl_event(struct domain *d,
+                              struct xen_domctl_monitor_op *mop)
 {
-    return -ENOSYS;
+    /* No arch-specific monitor vm-events on ARM.
+     *
+     * Should not be reached unless arch_monitor_get_capabilities() is not
+     * properly implemented. In that case, since reaching this point does
+     * not really break anything, don't crash the hypervisor, issue a
+     * warning instead of BUG().
+     */
+    printk(XENLOG_WARNING
+            "WARNING, BUG: arch_monitor_get_capabilities() not implemented"
+            "properly.\n");
+
+    return -EOPNOTSUPP;
 }
 
-#endif /* __ASM_X86_MONITOR_H__ */
+#endif /* __ASM_ARM_MONITOR_H__ */
diff --git a/xen/include/asm-x86/monitor.h b/xen/include/asm-x86/monitor.h
index 7c8280b..c789f71 100644
--- a/xen/include/asm-x86/monitor.h
+++ b/xen/include/asm-x86/monitor.h
@@ -1,9 +1,10 @@
 /*
  * include/asm-x86/monitor.h
  *
- * Architecture-specific monitor_op domctl handler.
+ * Arch-specific monitor_op domctl handler.
  *
  * Copyright (c) 2015 Tamas K Lengyel (tamas@tklengyel.com)
+ * Copyright (c) 2016, Bitdefender S.R.L.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public
@@ -21,11 +22,55 @@
 #ifndef __ASM_X86_MONITOR_H__
 #define __ASM_X86_MONITOR_H__
 
-struct domain;
-struct xen_domctl_monitor_op;
+#include <xen/sched.h>
+#include <public/domctl.h>
+#include <asm/cpufeature.h>
+#include <asm/hvm/hvm.h>
 
 #define monitor_ctrlreg_bitmask(ctrlreg_index) (1U << (ctrlreg_index))
 
-int monitor_domctl(struct domain *d, struct xen_domctl_monitor_op *op);
+static inline uint32_t arch_monitor_get_capabilities(struct domain *d)
+{
+    uint32_t capabilities = 0;
+
+    /*
+     * At the moment only Intel HVM domains are supported. However, event
+     * delivery could be extended to AMD and PV domains.
+     */
+    if ( !is_hvm_domain(d) || !cpu_has_vmx )
+        return capabilities;
+
+    capabilities = (1 << XEN_DOMCTL_MONITOR_EVENT_WRITE_CTRLREG) |
+                   (1 << XEN_DOMCTL_MONITOR_EVENT_MOV_TO_MSR) |
+                   (1 << XEN_DOMCTL_MONITOR_EVENT_SOFTWARE_BREAKPOINT) |
+                   (1 << XEN_DOMCTL_MONITOR_EVENT_GUEST_REQUEST);
+
+    /* Since we know this is on VMX, we can just call the hvm func */
+    if ( hvm_is_singlestep_supported() )
+        capabilities |= (1 << XEN_DOMCTL_MONITOR_EVENT_SINGLESTEP);
+
+    return capabilities;
+}
+
+static inline
+int arch_monitor_domctl_op(struct domain *d, struct xen_domctl_monitor_op *mop)
+{
+    switch ( mop->op )
+    {
+    case XEN_DOMCTL_MONITOR_OP_EMULATE_EACH_REP:
+        domain_pause(d);
+        d->arch.mem_access_emulate_each_rep = !!mop->event;
+        domain_unpause(d);
+        break;
+
+    default:
+        return -EOPNOTSUPP;
+    }
+
+    return 0;
+}
+
+int arch_monitor_domctl_event(struct domain *d,
+                              struct xen_domctl_monitor_op *mop);
 
 #endif /* __ASM_X86_MONITOR_H__ */
diff --git a/xen/include/xen/monitor.h b/xen/include/xen/monitor.h
new file mode 100644
index 0000000..ae49a39
--- /dev/null
+++ b/xen/include/xen/monitor.h
@@ -0,0 +1,30 @@
+/*
+ * include/xen/monitor.h
+ *
+ * Common monitor_op domctl handler.
+ *
+ * Copyright (c) 2015 Tamas K Lengyel (tamas@tklengyel.com)
+ * Copyright (c) 2016, Bitdefender S.R.L.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __MONITOR_H__
+#define __MONITOR_H__
+
+#include <xen/sched.h>
+#include <public/domctl.h>
+
+int monitor_domctl(struct domain *d, struct xen_domctl_monitor_op *op);
+
+#endif /* __MONITOR_H__ */
-- 
2.5.0