Current logic to handle long running operations is flawed because it
doesn't prevent the guest vcpu from running. Fix this by raising a
scheduler softirq when preemption is required, so that the do_softirq
call in the guest entry path performs a rescheduling. Also move the
call to vpci_process_pending into handle_hvm_io_completion, together
with the IOREQ code that handles pending IO instructions.
Note that a scheduler softirq is also raised when the long running
operation is queued in order to prevent the guest vcpu from resuming
execution.
Signed-off-by: Roger Pau Monné <roger....@citrix.com>
---
Cc: Paul Durrant <paul.durr...@citrix.com>
Cc: Jan Beulich <jbeul...@suse.com>
Cc: Andrew Cooper <andrew.coop...@citrix.com>
Cc: Wei Liu <wei.l...@citrix.com>
Cc: George Dunlap <george.dun...@eu.citrix.com>
Cc: Ian Jackson <ian.jack...@eu.citrix.com>
Cc: Julien Grall <julien.gr...@arm.com>
Cc: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
Cc: Stefano Stabellini <sstabell...@kernel.org>
Cc: Tim Deegan <t...@xen.org>
---
Changes since v4:
- Add a comment to clarify defer_map raising a scheduler softirq.
- Reword commit message.
- Raise the scheduler softirq in handle_hvm_io_completion rather than
vpci_process_pending.
Changes since v3:
- Don't use a tasklet.
---
xen/arch/x86/hvm/ioreq.c | 9 ++++++---
xen/drivers/vpci/header.c | 5 +++++
2 files changed, 11 insertions(+), 3 deletions(-)
diff --git a/xen/arch/x86/hvm/ioreq.c b/xen/arch/x86/hvm/ioreq.c
index a56d634f31..71f23227e6 100644
--- a/xen/arch/x86/hvm/ioreq.c
+++ b/xen/arch/x86/hvm/ioreq.c
@@ -85,9 +85,6 @@ bool hvm_io_pending(struct vcpu *v)
struct hvm_ioreq_server *s;
unsigned int id;
- if ( has_vpci(d) && vpci_process_pending(v) )
- return true;
-
FOR_EACH_IOREQ_SERVER(d, id, s)
{
struct hvm_ioreq_vcpu *sv;
@@ -186,6 +183,12 @@ bool handle_hvm_io_completion(struct vcpu *v)
enum hvm_io_completion io_completion;
unsigned int id;
+ if ( has_vpci(d) && vpci_process_pending(v) )
+ {
+ raise_softirq(SCHEDULE_SOFTIRQ);
+ return false;
+ }
+
FOR_EACH_IOREQ_SERVER(d, id, s)
{
struct hvm_ioreq_vcpu *sv;
diff --git a/xen/drivers/vpci/header.c b/xen/drivers/vpci/header.c
index 39dffb21fb..c9bdc2ced3 100644
--- a/xen/drivers/vpci/header.c
+++ b/xen/drivers/vpci/header.c
@@ -184,6 +184,11 @@ static void defer_map(struct domain *d, struct pci_dev
*pdev,
curr->vpci.mem = mem;
curr->vpci.cmd = cmd;
curr->vpci.rom_only = rom_only;
+ /*
+ * Raise a scheduler softirq in order to prevent the guest from resuming
+ * execution with pending mapping operations.
+ */
+ raise_softirq(SCHEDULE_SOFTIRQ);
}
static int modify_bars(const struct pci_dev *pdev, uint16_t cmd, bool rom_only)
--
2.19.1
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
