Re: [PATCH v5 3/3] vfio/pci: make use of irq_update_devid and optimize irq ops
在 2019/8/31 上午4:06, Alex Williamson 写道:
On Fri, 30 Aug 2019 16:42:06 +0800
Ben Luo wrote:
When userspace (e.g. qemu) triggers a switch between KVM
irqfd and userspace eventfd, only dev_id of irqaction
(i.e. the "trigger" in this patch's context) will be
changed, but a free-then-request-irq action is taken in
current code. And, irq affinity setting in VM will also
trigger a free-then-request-irq action, which actually
changes nothing, but only need to bounce the irqbypass
registraion in case that posted-interrupt is in use.
This patch makes use of irq_update_devid() and optimize
both cases above, which reduces the risk of losing interrupt
and also cuts some overhead.
Signed-off-by: Ben Luo
---
drivers/vfio/pci/vfio_pci_intrs.c | 124 ++
1 file changed, 87 insertions(+), 37 deletions(-)
diff --git a/drivers/vfio/pci/vfio_pci_intrs.c
b/drivers/vfio/pci/vfio_pci_intrs.c
index 3fa3f72..d3a93d7 100644
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@@ -284,70 +284,120 @@ static int vfio_msi_enable(struct vfio_pci_device *vdev,
int nvec, bool msix)
static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
int vector, int fd, bool msix)
{
+ struct eventfd_ctx *trigger = NULL;
struct pci_dev *pdev = vdev->pdev;
- struct eventfd_ctx *trigger;
int irq, ret;
if (vector < 0 || vector >= vdev->num_ctx)
return -EINVAL;
+ if (fd >= 0) {
+ trigger = eventfd_ctx_fdget(fd);
+ if (IS_ERR(trigger)) {
+ /* oops, going to disable this interrupt */
+ dev_info(>dev,
+"get ctx error on bad fd: %d for vector:%d\n",
+fd, vector);
I think a user could trigger this maliciously as a denial of service by
simply providing a bogus file descriptor. The user is informed of the
error by the return value, why do we need to spam the logs?
Ah, you are right, I will remove this log in next version
+ }
+ }
+
irq = pci_irq_vector(pdev, vector);
+ /*
+* 'trigger' is NULL or invalid, disable the interrupt
+* 'trigger' is same as before, only bounce the bypass registration
+* 'trigger' is a new invalid one, update it to irqaction and other
s/invalid/valid/
sorry for typo :)
+* data structures referencing to the old one; fallback to disable
+* the interrupt on error
+*/
if (vdev->ctx[vector].trigger) {
- free_irq(irq, vdev->ctx[vector].trigger);
+ /*
+* even if the trigger is unchanged we need to bounce the
+* interrupt bypass connection to allow affinity changes in
+* the guest to be realized.
+*/
irq_bypass_unregister_producer(>ctx[vector].producer);
- kfree(vdev->ctx[vector].name);
- eventfd_ctx_put(vdev->ctx[vector].trigger);
- vdev->ctx[vector].trigger = NULL;
+
+ if (vdev->ctx[vector].trigger == trigger) {
+ /* avoid duplicated referencing to the same trigger */
+ eventfd_ctx_put(trigger);
+
+ } else if (trigger && !IS_ERR(trigger)) {
+ ret = irq_update_devid(irq,
+ vdev->ctx[vector].trigger,
trigger);
+ if (unlikely(ret)) {
+ dev_info(>dev,
+"update devid of %d (token %p) failed:
%d\n",
+irq, vdev->ctx[vector].trigger, ret);
+ eventfd_ctx_put(trigger);
+ free_irq(irq, vdev->ctx[vector].trigger);
+ kfree(vdev->ctx[vector].name);
+ eventfd_ctx_put(vdev->ctx[vector].trigger);
+ vdev->ctx[vector].trigger = NULL;
+ return ret;
+ }
+ eventfd_ctx_put(vdev->ctx[vector].trigger);
+ vdev->ctx[vector].producer.token = trigger;
+ vdev->ctx[vector].trigger = trigger;
+
+ } else {
+ free_irq(irq, vdev->ctx[vector].trigger);
+ kfree(vdev->ctx[vector].name);
+ eventfd_ctx_put(vdev->ctx[vector].trigger);
+ vdev->ctx[vector].trigger = NULL;
+ }
}
if (fd < 0)
return 0;
+ else if (IS_ERR(trigger))
+ return PTR_ERR(trigger);
- vdev->ctx[vector].name = kasprintf(GFP_KERNEL, "vfio-msi%s[%d](%s)",
- msix ? "x" : "", vector,
-
Re: [PATCH v5 3/3] vfio/pci: make use of irq_update_devid and optimize irq ops
On Fri, 30 Aug 2019 16:42:06 +0800
Ben Luo wrote:
> When userspace (e.g. qemu) triggers a switch between KVM
> irqfd and userspace eventfd, only dev_id of irqaction
> (i.e. the "trigger" in this patch's context) will be
> changed, but a free-then-request-irq action is taken in
> current code. And, irq affinity setting in VM will also
> trigger a free-then-request-irq action, which actually
> changes nothing, but only need to bounce the irqbypass
> registraion in case that posted-interrupt is in use.
>
> This patch makes use of irq_update_devid() and optimize
> both cases above, which reduces the risk of losing interrupt
> and also cuts some overhead.
>
> Signed-off-by: Ben Luo
> ---
> drivers/vfio/pci/vfio_pci_intrs.c | 124
> ++
> 1 file changed, 87 insertions(+), 37 deletions(-)
>
> diff --git a/drivers/vfio/pci/vfio_pci_intrs.c
> b/drivers/vfio/pci/vfio_pci_intrs.c
> index 3fa3f72..d3a93d7 100644
> --- a/drivers/vfio/pci/vfio_pci_intrs.c
> +++ b/drivers/vfio/pci/vfio_pci_intrs.c
> @@ -284,70 +284,120 @@ static int vfio_msi_enable(struct vfio_pci_device
> *vdev, int nvec, bool msix)
> static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
> int vector, int fd, bool msix)
> {
> + struct eventfd_ctx *trigger = NULL;
> struct pci_dev *pdev = vdev->pdev;
> - struct eventfd_ctx *trigger;
> int irq, ret;
>
> if (vector < 0 || vector >= vdev->num_ctx)
> return -EINVAL;
>
> + if (fd >= 0) {
> + trigger = eventfd_ctx_fdget(fd);
> + if (IS_ERR(trigger)) {
> + /* oops, going to disable this interrupt */
> + dev_info(>dev,
> + "get ctx error on bad fd: %d for vector:%d\n",
> + fd, vector);
I think a user could trigger this maliciously as a denial of service by
simply providing a bogus file descriptor. The user is informed of the
error by the return value, why do we need to spam the logs?
> + }
> + }
> +
> irq = pci_irq_vector(pdev, vector);
>
> + /*
> + * 'trigger' is NULL or invalid, disable the interrupt
> + * 'trigger' is same as before, only bounce the bypass registration
> + * 'trigger' is a new invalid one, update it to irqaction and other
s/invalid/valid/
> + * data structures referencing to the old one; fallback to disable
> + * the interrupt on error
> + */
> if (vdev->ctx[vector].trigger) {
> - free_irq(irq, vdev->ctx[vector].trigger);
> + /*
> + * even if the trigger is unchanged we need to bounce the
> + * interrupt bypass connection to allow affinity changes in
> + * the guest to be realized.
> + */
> irq_bypass_unregister_producer(>ctx[vector].producer);
> - kfree(vdev->ctx[vector].name);
> - eventfd_ctx_put(vdev->ctx[vector].trigger);
> - vdev->ctx[vector].trigger = NULL;
> +
> + if (vdev->ctx[vector].trigger == trigger) {
> + /* avoid duplicated referencing to the same trigger */
> + eventfd_ctx_put(trigger);
> +
> + } else if (trigger && !IS_ERR(trigger)) {
> + ret = irq_update_devid(irq,
> +vdev->ctx[vector].trigger,
> trigger);
> + if (unlikely(ret)) {
> + dev_info(>dev,
> + "update devid of %d (token %p) failed:
> %d\n",
> + irq, vdev->ctx[vector].trigger, ret);
> + eventfd_ctx_put(trigger);
> + free_irq(irq, vdev->ctx[vector].trigger);
> + kfree(vdev->ctx[vector].name);
> + eventfd_ctx_put(vdev->ctx[vector].trigger);
> + vdev->ctx[vector].trigger = NULL;
> + return ret;
> + }
> + eventfd_ctx_put(vdev->ctx[vector].trigger);
> + vdev->ctx[vector].producer.token = trigger;
> + vdev->ctx[vector].trigger = trigger;
> +
> + } else {
> + free_irq(irq, vdev->ctx[vector].trigger);
> + kfree(vdev->ctx[vector].name);
> + eventfd_ctx_put(vdev->ctx[vector].trigger);
> + vdev->ctx[vector].trigger = NULL;
> + }
> }
>
> if (fd < 0)
> return 0;
> + else if (IS_ERR(trigger))
> + return PTR_ERR(trigger);
>
> - vdev->ctx[vector].name = kasprintf(GFP_KERNEL, "vfio-msi%s[%d](%s)",
> -msix ? "x" : "", vector,
> -pci_name(pdev));
> - if
[PATCH v5 3/3] vfio/pci: make use of irq_update_devid and optimize irq ops
When userspace (e.g. qemu) triggers a switch between KVM
irqfd and userspace eventfd, only dev_id of irqaction
(i.e. the "trigger" in this patch's context) will be
changed, but a free-then-request-irq action is taken in
current code. And, irq affinity setting in VM will also
trigger a free-then-request-irq action, which actually
changes nothing, but only need to bounce the irqbypass
registraion in case that posted-interrupt is in use.
This patch makes use of irq_update_devid() and optimize
both cases above, which reduces the risk of losing interrupt
and also cuts some overhead.
Signed-off-by: Ben Luo
---
drivers/vfio/pci/vfio_pci_intrs.c | 124 ++
1 file changed, 87 insertions(+), 37 deletions(-)
diff --git a/drivers/vfio/pci/vfio_pci_intrs.c
b/drivers/vfio/pci/vfio_pci_intrs.c
index 3fa3f72..d3a93d7 100644
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@@ -284,70 +284,120 @@ static int vfio_msi_enable(struct vfio_pci_device *vdev,
int nvec, bool msix)
static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
int vector, int fd, bool msix)
{
+ struct eventfd_ctx *trigger = NULL;
struct pci_dev *pdev = vdev->pdev;
- struct eventfd_ctx *trigger;
int irq, ret;
if (vector < 0 || vector >= vdev->num_ctx)
return -EINVAL;
+ if (fd >= 0) {
+ trigger = eventfd_ctx_fdget(fd);
+ if (IS_ERR(trigger)) {
+ /* oops, going to disable this interrupt */
+ dev_info(>dev,
+"get ctx error on bad fd: %d for vector:%d\n",
+fd, vector);
+ }
+ }
+
irq = pci_irq_vector(pdev, vector);
+ /*
+* 'trigger' is NULL or invalid, disable the interrupt
+* 'trigger' is same as before, only bounce the bypass registration
+* 'trigger' is a new invalid one, update it to irqaction and other
+* data structures referencing to the old one; fallback to disable
+* the interrupt on error
+*/
if (vdev->ctx[vector].trigger) {
- free_irq(irq, vdev->ctx[vector].trigger);
+ /*
+* even if the trigger is unchanged we need to bounce the
+* interrupt bypass connection to allow affinity changes in
+* the guest to be realized.
+*/
irq_bypass_unregister_producer(>ctx[vector].producer);
- kfree(vdev->ctx[vector].name);
- eventfd_ctx_put(vdev->ctx[vector].trigger);
- vdev->ctx[vector].trigger = NULL;
+
+ if (vdev->ctx[vector].trigger == trigger) {
+ /* avoid duplicated referencing to the same trigger */
+ eventfd_ctx_put(trigger);
+
+ } else if (trigger && !IS_ERR(trigger)) {
+ ret = irq_update_devid(irq,
+ vdev->ctx[vector].trigger,
trigger);
+ if (unlikely(ret)) {
+ dev_info(>dev,
+"update devid of %d (token %p) failed:
%d\n",
+irq, vdev->ctx[vector].trigger, ret);
+ eventfd_ctx_put(trigger);
+ free_irq(irq, vdev->ctx[vector].trigger);
+ kfree(vdev->ctx[vector].name);
+ eventfd_ctx_put(vdev->ctx[vector].trigger);
+ vdev->ctx[vector].trigger = NULL;
+ return ret;
+ }
+ eventfd_ctx_put(vdev->ctx[vector].trigger);
+ vdev->ctx[vector].producer.token = trigger;
+ vdev->ctx[vector].trigger = trigger;
+
+ } else {
+ free_irq(irq, vdev->ctx[vector].trigger);
+ kfree(vdev->ctx[vector].name);
+ eventfd_ctx_put(vdev->ctx[vector].trigger);
+ vdev->ctx[vector].trigger = NULL;
+ }
}
if (fd < 0)
return 0;
+ else if (IS_ERR(trigger))
+ return PTR_ERR(trigger);
- vdev->ctx[vector].name = kasprintf(GFP_KERNEL, "vfio-msi%s[%d](%s)",
- msix ? "x" : "", vector,
- pci_name(pdev));
- if (!vdev->ctx[vector].name)
- return -ENOMEM;
+ if (!vdev->ctx[vector].trigger) {
+ vdev->ctx[vector].name = kasprintf(GFP_KERNEL,
+ "vfio-msi%s[%d](%s)",
+ msix ? "x" : "", vector,
+
