It's hardly ever correct to check for just DOMID_SELF, as guests have
ways to figure out their domain IDs and hence could instead use those as
inputs to respective hypercalls. Note, however, that for ordinary DomU-s
the adjustment is relaxing things rather than tightening them, since
- as a result of XSA-237 - the respective XSM checks would have rejected
self (un)mapping attempts for other than the control domain.
Since in physdev_map_pirq() handling overall is a little easier this
way, move obtaining of the domain pointer into the caller. Doing the
same for physdev_unmap_pirq() is just to keep both consistent in this
regard. For both this has the advantage that it is now provable (by the
build not failing) that there are no DOMID_SELF checks left (and none
could easily be re-added).
Fixes: 0b469cd68708 ("Interrupt remapping to PIRQs in HVM guests")
Fixes: 9e1a3415b773 ("x86: fixes after emuirq changes")
Signed-off-by: Jan Beulich <jbeul...@suse.com>
---
Note that the moving of rcu_lock_domain_by_any_id() is also going to
help
https://lists.xen.org/archives/html/xen-devel/2024-06/msg00206.html.
--- a/xen/arch/x86/physdev.c
+++ b/xen/arch/x86/physdev.c
@@ -18,9 +18,9 @@
#include <xsm/xsm.h>
#include <asm/p2m.h>
-int physdev_map_pirq(domid_t domid, int type, int *index, int *pirq_p,
+int physdev_map_pirq(struct domain *d, int type, int *index, int *pirq_p,
struct msi_info *msi);
-int physdev_unmap_pirq(domid_t domid, int pirq);
+int physdev_unmap_pirq(struct domain *d, int pirq);
#include "x86_64/mmconfig.h"
@@ -88,13 +88,12 @@ static int physdev_hvm_map_pirq(
return ret;
}
-int physdev_map_pirq(domid_t domid, int type, int *index, int *pirq_p,
+int physdev_map_pirq(struct domain *d, int type, int *index, int *pirq_p,
struct msi_info *msi)
{
- struct domain *d = current->domain;
int ret;
- if ( domid == DOMID_SELF && is_hvm_domain(d) && has_pirq(d) )
+ if ( d == current->domain && is_hvm_domain(d) && has_pirq(d) )
{
/*
* Only makes sense for vector-based callback, else HVM-IRQ logic
@@ -106,13 +105,9 @@ int physdev_map_pirq(domid_t domid, int
return physdev_hvm_map_pirq(d, type, index, pirq_p);
}
- d = rcu_lock_domain_by_any_id(domid);
- if ( d == NULL )
- return -ESRCH;
-
ret = xsm_map_domain_pirq(XSM_DM_PRIV, d);
if ( ret )
- goto free_domain;
+ return ret;
/* Verify or get irq. */
switch ( type )
@@ -135,24 +130,17 @@ int physdev_map_pirq(domid_t domid, int
break;
}
- free_domain:
- rcu_unlock_domain(d);
return ret;
}
-int physdev_unmap_pirq(domid_t domid, int pirq)
+int physdev_unmap_pirq(struct domain *d, int pirq)
{
- struct domain *d;
int ret = 0;
- d = rcu_lock_domain_by_any_id(domid);
- if ( d == NULL )
- return -ESRCH;
-
- if ( domid != DOMID_SELF || !is_hvm_domain(d) || !has_pirq(d) )
+ if ( d != current->domain || !is_hvm_domain(d) || !has_pirq(d) )
ret = xsm_unmap_domain_pirq(XSM_DM_PRIV, d);
if ( ret )
- goto free_domain;
+ return ret;
if ( is_hvm_domain(d) && has_pirq(d) )
{
@@ -160,8 +148,8 @@ int physdev_unmap_pirq(domid_t domid, in
if ( domain_pirq_to_emuirq(d, pirq) != IRQ_UNBOUND )
ret = unmap_domain_pirq_emuirq(d, pirq);
write_unlock(&d->event_lock);
- if ( domid == DOMID_SELF || ret )
- goto free_domain;
+ if ( d == current->domain || ret )
+ return ret;
}
pcidevs_lock();
@@ -170,8 +158,6 @@ int physdev_unmap_pirq(domid_t domid, in
write_unlock(&d->event_lock);
pcidevs_unlock();
- free_domain:
- rcu_unlock_domain(d);
return ret;
}
#endif /* COMPAT */
@@ -184,6 +170,8 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_H
switch ( cmd )
{
+ struct domain *d;
+
case PHYSDEVOP_eoi: {
struct physdev_eoi eoi;
struct pirq *pirq;
@@ -331,8 +319,15 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_H
msi.sbdf.devfn = map.devfn;
msi.entry_nr = map.entry_nr;
msi.table_base = map.table_base;
- ret = physdev_map_pirq(map.domid, map.type, &map.index, &map.pirq,
- &msi);
+
+ d = rcu_lock_domain_by_any_id(map.domid);
+ ret = -ESRCH;
+ if ( !d )
+ break;
+
+ ret = physdev_map_pirq(d, map.type, &map.index, &map.pirq, &msi);
+
+ rcu_unlock_domain(d);
if ( map.type == MAP_PIRQ_TYPE_MULTI_MSI )
map.entry_nr = msi.entry_nr;
@@ -348,7 +343,15 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_H
if ( copy_from_guest(&unmap, arg, 1) != 0 )
break;
- ret = physdev_unmap_pirq(unmap.domid, unmap.pirq);
+ d = rcu_lock_domain_by_any_id(unmap.domid);
+ ret = -ESRCH;
+ if ( !d )
+ break;
+
+ ret = physdev_unmap_pirq(d, unmap.pirq);
+
+ rcu_unlock_domain(d);
+
break;
}
