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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 2/4] x86/hvm: take a reference on ioreq server emulating domain
When an ioreq server is created the code currently stores the id
of the emulating domain, but does not take a reference on that domain.
This patch modifies the code to hold a reference for the lifetime of the
ioreq server.
NOTE: For the default server only it is theoritically possible for the
emulating domain to change during the lifetime of the ioreq server
(if a tools domain modifies HVM_PARAM_DM_DOMAIN) so this domain
references are swizzled in this case.
Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
xen/arch/x86/hvm/ioreq.c | 102 +++++++++++++++++++++++++++------------
xen/include/asm-x86/hvm/domain.h | 4 +-
2 files changed, 73 insertions(+), 33 deletions(-)
diff --git a/xen/arch/x86/hvm/ioreq.c b/xen/arch/x86/hvm/ioreq.c
index ee5f47de65..8d1ff46146 100644
--- a/xen/arch/x86/hvm/ioreq.c
+++ b/xen/arch/x86/hvm/ioreq.c
@@ -218,7 +218,7 @@ static void hvm_unmap_ioreq_page(struct hvm_ioreq_server
*s, bool buf)
static int hvm_map_ioreq_page(
struct hvm_ioreq_server *s, bool buf, unsigned long gfn)
{
- struct domain *d = s->domain;
+ struct domain *d = s->target;
struct hvm_ioreq_page *iorp = buf ? &s->bufioreq : &s->ioreq;
struct page_info *page;
void *va;
@@ -305,6 +305,7 @@ static int hvm_ioreq_server_add_vcpu(struct
hvm_ioreq_server *s,
bool is_default, struct vcpu *v)
{
struct hvm_ioreq_vcpu *sv;
+ domid_t domid;
int rc;
sv = xzalloc(struct hvm_ioreq_vcpu);
@@ -315,7 +316,9 @@ static int hvm_ioreq_server_add_vcpu(struct
hvm_ioreq_server *s,
spin_lock(&s->lock);
- rc = alloc_unbound_xen_event_channel(v->domain, v->vcpu_id, s->domid,
+ domid = s->emulator->domain_id;
+
+ rc = alloc_unbound_xen_event_channel(v->domain, v->vcpu_id, domid,
NULL);
if ( rc < 0 )
goto fail2;
@@ -324,9 +327,9 @@ static int hvm_ioreq_server_add_vcpu(struct
hvm_ioreq_server *s,
if ( v->vcpu_id == 0 && s->bufioreq.va != NULL )
{
- struct domain *d = s->domain;
+ struct domain *d = s->target;
- rc = alloc_unbound_xen_event_channel(v->domain, 0, s->domid, NULL);
+ rc = alloc_unbound_xen_event_channel(v->domain, 0, domid, NULL);
if ( rc < 0 )
goto fail3;
@@ -434,7 +437,7 @@ static int hvm_ioreq_server_setup_pages(struct
hvm_ioreq_server *s,
bool is_default,
bool handle_bufioreq)
{
- struct domain *d = s->domain;
+ struct domain *d = s->target;
unsigned long ioreq_gfn = gfn_x(INVALID_GFN);
unsigned long bufioreq_gfn = gfn_x(INVALID_GFN);
int rc;
@@ -471,7 +474,7 @@ static int hvm_ioreq_server_setup_pages(struct
hvm_ioreq_server *s,
static void hvm_ioreq_server_unmap_pages(struct hvm_ioreq_server *s,
bool is_default)
{
- struct domain *d = s->domain;
+ struct domain *d = s->target;
bool handle_bufioreq = !!s->bufioreq.va;
if ( handle_bufioreq )
@@ -521,7 +524,7 @@ static int hvm_ioreq_server_alloc_rangesets(struct
hvm_ioreq_server *s,
if ( rc )
goto fail;
- s->range[i] = rangeset_new(s->domain, name,
+ s->range[i] = rangeset_new(s->target, name,
RANGESETF_prettyprint_hex);
xfree(name);
@@ -545,7 +548,7 @@ static int hvm_ioreq_server_alloc_rangesets(struct
hvm_ioreq_server *s,
static void hvm_ioreq_server_enable(struct hvm_ioreq_server *s,
bool is_default)
{
- struct domain *d = s->domain;
+ struct domain *d = s->target;
struct hvm_ioreq_vcpu *sv;
bool handle_bufioreq = !!s->bufioreq.va;
@@ -576,7 +579,7 @@ static void hvm_ioreq_server_enable(struct hvm_ioreq_server
*s,
static void hvm_ioreq_server_disable(struct hvm_ioreq_server *s,
bool is_default)
{
- struct domain *d = s->domain;
+ struct domain *d = s->target;
bool handle_bufioreq = !!s->bufioreq.va;
spin_lock(&s->lock);
@@ -598,6 +601,20 @@ static void hvm_ioreq_server_disable(struct
hvm_ioreq_server *s,
spin_unlock(&s->lock);
}
+static int get_default_emulator(domid_t domid, struct domain **emulator)
+{
+ bool ref;
+
+ *emulator = rcu_lock_domain_by_id(domid);
+ if ( !*emulator )
+ return -ESRCH;
+
+ ref = !!get_domain(*emulator); /* fails if domain is dying */
+ rcu_unlock_domain(*emulator);
+
+ return ref ? 0 : -EACCES;
+}
+
static int hvm_ioreq_server_init(struct hvm_ioreq_server *s,
struct domain *d, bool is_default,
int bufioreq_handling, ioservid_t id)
@@ -606,11 +623,23 @@ static int hvm_ioreq_server_init(struct hvm_ioreq_server
*s,
int rc;
s->id = id;
- s->domain = d;
+ s->target = d;
- s->domid = is_default ?
- d->arch.hvm_domain.params[HVM_PARAM_DM_DOMAIN] :
- current->domain->domain_id;
+ if ( is_default )
+ {
+ domid_t domid = d->arch.hvm_domain.params[HVM_PARAM_DM_DOMAIN];
+
+ rc = get_default_emulator(domid, &s->emulator);
+ if ( rc )
+ return rc;
+ } else {
+ struct domain *currd = current->domain;
+
+ if ( !get_domain(currd) )
+ return -EACCES;
+
+ s->emulator = currd;
+ }
spin_lock_init(&s->lock);
INIT_LIST_HEAD(&s->ioreq_vcpu_list);
@@ -654,6 +683,8 @@ static void hvm_ioreq_server_deinit(struct hvm_ioreq_server
*s,
hvm_ioreq_server_remove_all_vcpus(s);
hvm_ioreq_server_unmap_pages(s, is_default);
hvm_ioreq_server_free_rangesets(s, is_default);
+
+ put_domain(s->emulator);
}
static ioservid_t next_ioservid(struct domain *d)
@@ -1125,35 +1156,46 @@ int hvm_set_dm_domain(struct domain *d, domid_t domid)
domain_pause(d);
spin_lock(&s->lock);
- if ( s->domid != domid )
+ if ( domid != s->emulator->domain_id )
{
- struct hvm_ioreq_vcpu *sv;
+ struct domain *emulator;
- list_for_each_entry ( sv,
- &s->ioreq_vcpu_list,
- list_entry )
+ rc = get_default_emulator(domid, &emulator);
+ if ( !rc )
{
- struct vcpu *v = sv->vcpu;
+ struct hvm_ioreq_vcpu *sv;
- if ( v->vcpu_id == 0 )
+ list_for_each_entry ( sv,
+ &s->ioreq_vcpu_list,
+ list_entry )
{
+ struct vcpu *v = sv->vcpu;
+
+ if ( v->vcpu_id == 0 )
+ {
+ rc = hvm_replace_event_channel(v, domid,
+ &s->bufioreq_evtchn);
+ if ( rc )
+ break;
+
+ d->arch.hvm_domain.params[HVM_PARAM_BUFIOREQ_EVTCHN] =
+ s->bufioreq_evtchn;
+ }
+
rc = hvm_replace_event_channel(v, domid,
- &s->bufioreq_evtchn);
+ &sv->ioreq_evtchn);
if ( rc )
break;
- d->arch.hvm_domain.params[HVM_PARAM_BUFIOREQ_EVTCHN] =
- s->bufioreq_evtchn;
+ hvm_update_ioreq_evtchn(s, sv);
}
- rc = hvm_replace_event_channel(v, domid, &sv->ioreq_evtchn);
- if ( rc )
- break;
-
- hvm_update_ioreq_evtchn(s, sv);
+ if ( !rc )
+ {
+ put_domain(s->emulator);
+ s->emulator = emulator;
+ }
}
-
- s->domid = domid;
}
spin_unlock(&s->lock);
diff --git a/xen/include/asm-x86/hvm/domain.h b/xen/include/asm-x86/hvm/domain.h
index 7f128c05ff..6e03d024c8 100644
--- a/xen/include/asm-x86/hvm/domain.h
+++ b/xen/include/asm-x86/hvm/domain.h
@@ -53,13 +53,11 @@ struct hvm_ioreq_vcpu {
struct hvm_ioreq_server {
struct list_head list_entry;
- struct domain *domain;
+ struct domain *target, *emulator;
/* Lock to serialize toolstack modifications */
spinlock_t lock;
- /* Domain id of emulating domain */
- domid_t domid;
ioservid_t id;
struct hvm_ioreq_page ioreq;
struct list_head ioreq_vcpu_list;
--
2.11.0
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