[PATCH v3.1 01/15] xen/x86: remove XENFEAT_hvm_pirqs for PVHv2 guests

[Roger Pau Monne <roger.pau@citrix.com>]

PVHv2 guests, unlike HVM guests, won't have the option to route interrupts
from physical or emulated devices over event channels using PIRQs. This
applies to both DomU and Dom0 PVHv2 guests.

Introduce a new XEN_X86_EMU_USE_PIRQ to notify Xen whether a HVM guest can
route physical interrupts (even from emulated devices) over event channels,
and is thus allowed to use some of the PHYSDEV ops.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
---
Changes since v2:
 - Change local variable name to currd instead of d.
 - Use currd where it makes sense.
---
 xen/arch/x86/hvm/hvm.c            | 25 ++++++++++++++++---------
 xen/arch/x86/physdev.c            |  5 +++--
 xen/common/kernel.c               |  3 ++-
 xen/include/public/arch-x86/xen.h |  4 +++-
 4 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 11e2b82..e516b20 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4164,10 +4164,12 @@ static long hvm_memory_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
 
 static long hvm_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
 {
+    struct domain *currd = current->domain;
+
     switch ( cmd )
     {
     default:
-        if ( !is_pvh_vcpu(current) || !is_hardware_domain(current->domain) )
+        if ( !is_pvh_domain(currd) || !is_hardware_domain(currd) )
             return -ENOSYS;
         /* fall through */
     case PHYSDEVOP_map_pirq:
@@ -4175,7 +4177,9 @@ static long hvm_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
     case PHYSDEVOP_eoi:
     case PHYSDEVOP_irq_status_query:
     case PHYSDEVOP_get_free_pirq:
-        return do_physdev_op(cmd, arg);
+        return ((currd->arch.emulation_flags & XEN_X86_EMU_USE_PIRQ) ||
+               is_pvh_domain(currd)) ?
+                    do_physdev_op(cmd, arg) : -ENOSYS;
     }
 }
 
@@ -4208,17 +4212,20 @@ static long hvm_memory_op_compat32(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
 static long hvm_physdev_op_compat32(
     int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
 {
+    struct domain *d = current->domain;
+
     switch ( cmd )
     {
-        case PHYSDEVOP_map_pirq:
-        case PHYSDEVOP_unmap_pirq:
-        case PHYSDEVOP_eoi:
-        case PHYSDEVOP_irq_status_query:
-        case PHYSDEVOP_get_free_pirq:
-            return compat_physdev_op(cmd, arg);
+    case PHYSDEVOP_map_pirq:
+    case PHYSDEVOP_unmap_pirq:
+    case PHYSDEVOP_eoi:
+    case PHYSDEVOP_irq_status_query:
+    case PHYSDEVOP_get_free_pirq:
+        return (d->arch.emulation_flags & XEN_X86_EMU_USE_PIRQ) ?
+                    compat_physdev_op(cmd, arg) : -ENOSYS;
         break;
     default:
-            return -ENOSYS;
+        return -ENOSYS;
         break;
     }
 }
diff --git a/xen/arch/x86/physdev.c b/xen/arch/x86/physdev.c
index 5a49796..0bea6e1 100644
--- a/xen/arch/x86/physdev.c
+++ b/xen/arch/x86/physdev.c
@@ -94,7 +94,8 @@ int physdev_map_pirq(domid_t domid, int type, int *index, int *pirq_p,
     int pirq, irq, ret = 0;
     void *map_data = NULL;
 
-    if ( domid == DOMID_SELF && is_hvm_domain(d) )
+    if ( domid == DOMID_SELF && is_hvm_domain(d) &&
+         (d->arch.emulation_flags & XEN_X86_EMU_USE_PIRQ) )
     {
         /*
          * Only makes sense for vector-based callback, else HVM-IRQ logic
@@ -265,7 +266,7 @@ int physdev_unmap_pirq(domid_t domid, int pirq)
     if ( ret )
         goto free_domain;
 
-    if ( is_hvm_domain(d) )
+    if ( is_hvm_domain(d) && (d->arch.emulation_flags & XEN_X86_EMU_USE_PIRQ) )
     {
         spin_lock(&d->event_lock);
         if ( domain_pirq_to_emuirq(d, pirq) != IRQ_UNBOUND )
diff --git a/xen/common/kernel.c b/xen/common/kernel.c
index d0edb13..a82f55f 100644
--- a/xen/common/kernel.c
+++ b/xen/common/kernel.c
@@ -332,7 +332,8 @@ DO(xen_version)(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
             case guest_type_hvm:
                 fi.submap |= (1U << XENFEAT_hvm_safe_pvclock) |
                              (1U << XENFEAT_hvm_callback_vector) |
-                             (1U << XENFEAT_hvm_pirqs);
+                             ((d->arch.emulation_flags & XEN_X86_EMU_USE_PIRQ) ?
+                                 (1U << XENFEAT_hvm_pirqs) : 0);
                 break;
             }
 #endif
diff --git a/xen/include/public/arch-x86/xen.h b/xen/include/public/arch-x86/xen.h
index cdd93c1..da6f4f2 100644
--- a/xen/include/public/arch-x86/xen.h
+++ b/xen/include/public/arch-x86/xen.h
@@ -283,12 +283,14 @@ struct xen_arch_domainconfig {
 #define XEN_X86_EMU_IOMMU           (1U<<_XEN_X86_EMU_IOMMU)
 #define _XEN_X86_EMU_PIT            8
 #define XEN_X86_EMU_PIT             (1U<<_XEN_X86_EMU_PIT)
+#define _XEN_X86_EMU_USE_PIRQ       9
+#define XEN_X86_EMU_USE_PIRQ        (1U<<_XEN_X86_EMU_USE_PIRQ)
 
 #define XEN_X86_EMU_ALL             (XEN_X86_EMU_LAPIC | XEN_X86_EMU_HPET |  \
                                      XEN_X86_EMU_PM | XEN_X86_EMU_RTC |      \
                                      XEN_X86_EMU_IOAPIC | XEN_X86_EMU_PIC |  \
                                      XEN_X86_EMU_VGA | XEN_X86_EMU_IOMMU |   \
-                                     XEN_X86_EMU_PIT)
+                                     XEN_X86_EMU_PIT | XEN_X86_EMU_USE_PIRQ)
     uint32_t emulation_flags;
 };
 #endif
-- 
2.7.4 (Apple Git-66)


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