diff mbox

[v8,3/6] kvm: Add IRQ source ID option to KVM_IRQFD

Message ID 20120810223731.809.67249.stgit@bling.home (mailing list archive)
State New, archived
Headers show

Commit Message

Alex Williamson Aug. 10, 2012, 10:37 p.m. UTC 
This allows specifying an IRQ source ID to be used when injecting an
interrupt.  When not specified KVM_USERSPACE_IRQ_SOURCE_ID is used.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---

 Documentation/virtual/kvm/api.txt |    5 +++++
 arch/x86/kvm/x86.c                |    1 +
 include/linux/kvm.h               |    6 +++++-
 virt/kvm/eventfd.c                |   14 ++++++++++----
 4 files changed, 21 insertions(+), 5 deletions(-)


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Comments

Michael S. Tsirkin Aug. 15, 2012, 1:49 p.m. UTC | #1 
On Fri, Aug 10, 2012 at 04:37:33PM -0600, Alex Williamson wrote:
> This allows specifying an IRQ source ID to be used when injecting an
> interrupt.  When not specified KVM_USERSPACE_IRQ_SOURCE_ID is used.
> 
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> ---
> 
>  Documentation/virtual/kvm/api.txt |    5 +++++
>  arch/x86/kvm/x86.c                |    1 +
>  include/linux/kvm.h               |    6 +++++-
>  virt/kvm/eventfd.c                |   14 ++++++++++----
>  4 files changed, 21 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 062cfd5..46f4b4d 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -1946,6 +1946,11 @@ the guest using the specified gsi pin.  The irqfd is removed using
>  the KVM_IRQFD_FLAG_DEASSIGN flag, specifying both kvm_irqfd.fd
>  and kvm_irqfd.gsi.
>  
> +When KVM_CAP_IRQFD_IRQ_SOURCE_ID is available, KVM_IRQFD supports the
> +KVM_IRQFD_FLAG_IRQ_SOURCE_ID which can be used to specify an IRQ
> +source ID (see KVM_IRQ_SOURCE_ID) to be used for the guest interrupt.
> +This flag has no effect on deassignment.
> +
>  4.76 KVM_PPC_ALLOCATE_HTAB
>  
>  Capability: KVM_CAP_PPC_ALLOC_HTAB
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 75e743e..946c5bd 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2174,6 +2174,7 @@ int kvm_dev_ioctl_check_extension(long ext)
>  	case KVM_CAP_GET_TSC_KHZ:
>  	case KVM_CAP_PCI_2_3:
>  	case KVM_CAP_KVMCLOCK_CTRL:
> +	case KVM_CAP_IRQFD_IRQ_SOURCE_ID:
>  		r = 1;
>  		break;
>  	case KVM_CAP_COALESCED_MMIO:
> diff --git a/include/linux/kvm.h b/include/linux/kvm.h
> index 67b6b49..deda8a9 100644
> --- a/include/linux/kvm.h
> +++ b/include/linux/kvm.h
> @@ -619,6 +619,7 @@ struct kvm_ppc_smmu_info {
>  #define KVM_CAP_S390_COW 79
>  #define KVM_CAP_PPC_ALLOC_HTAB 80
>  #define KVM_CAP_NR_IRQ_SOURCE_ID 81
> +#define KVM_CAP_IRQFD_IRQ_SOURCE_ID 82
>  
>  #ifdef KVM_CAP_IRQ_ROUTING
>  
> @@ -684,12 +685,15 @@ struct kvm_xen_hvm_config {
>  #endif
>  
>  #define KVM_IRQFD_FLAG_DEASSIGN (1 << 0)
> +/* Available with KVM_CAP_IRQFD_IRQ_SOURCE_ID */
> +#define KVM_IRQFD_FLAG_IRQ_SOURCE_ID (1 << 1)
>  
>  struct kvm_irqfd {
>  	__u32 fd;
>  	__u32 gsi;
>  	__u32 flags;
> -	__u8  pad[20];
> +	__u32 irq_source_id;
> +	__u8  pad[16];
>  };
>  
>  #define KVM_IRQ_SOURCE_ID_FLAG_DEASSIGN (1 << 0)
> diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
> index 7d7e2aa..30150f1 100644
> --- a/virt/kvm/eventfd.c
> +++ b/virt/kvm/eventfd.c
> @@ -51,6 +51,7 @@ struct _irqfd {
>  	struct kvm_kernel_irq_routing_entry __rcu *irq_entry;
>  	/* Used for level IRQ fast-path */
>  	int gsi;
> +	int irq_source_id;
>  	struct work_struct inject;
>  	/* Used for setup/shutdown */
>  	struct eventfd_ctx *eventfd;
> @@ -67,8 +68,8 @@ irqfd_inject(struct work_struct *work)
>  	struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
>  	struct kvm *kvm = irqfd->kvm;
>  
> -	kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1);
> -	kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0);
> +	kvm_set_irq(kvm, irqfd->irq_source_id, irqfd->gsi, 1);
> +	kvm_set_irq(kvm, irqfd->irq_source_id, irqfd->gsi, 0);

Looks like this can lead to kernel data corruption if irq_source_id
specified it out of range?

>  }
>  
>  /*
> @@ -138,7 +139,7 @@ irqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key)
>  		irq = rcu_dereference(irqfd->irq_entry);
>  		/* An event has been signaled, inject an interrupt */
>  		if (irq)
> -			kvm_set_msi(irq, kvm, KVM_USERSPACE_IRQ_SOURCE_ID, 1);
> +			kvm_set_msi(irq, kvm, irqfd->irq_source_id, 1);
>  		else
>  			schedule_work(&irqfd->inject);
>  		rcu_read_unlock();
> @@ -213,6 +214,10 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
>  
>  	irqfd->kvm = kvm;
>  	irqfd->gsi = args->gsi;
> +	if (args->flags & KVM_IRQFD_FLAG_IRQ_SOURCE_ID)
> +		irqfd->irq_source_id = args->irq_source_id;
> +	else
> +		irqfd->irq_source_id = KVM_USERSPACE_IRQ_SOURCE_ID;

As in the previous patch, there is no validation
that source id was previously allocated to userspace, so this makes life
harder for userspace: if it deassigns a used source ID the result is not
a clean failure but hard to find bugs.

>  	INIT_LIST_HEAD(&irqfd->list);
>  	INIT_WORK(&irqfd->inject, irqfd_inject);
>  	INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
> @@ -340,7 +345,8 @@ kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
>  int
>  kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
>  {
> -	if (args->flags & ~KVM_IRQFD_FLAG_DEASSIGN)
> +	if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN |
> +			    KVM_IRQFD_FLAG_IRQ_SOURCE_ID))
>  		return -EINVAL;
>  
>  	if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)
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Alex Williamson Aug. 15, 2012, 5:08 p.m. UTC | #2 
On Wed, 2012-08-15 at 16:49 +0300, Michael S. Tsirkin wrote:
> On Fri, Aug 10, 2012 at 04:37:33PM -0600, Alex Williamson wrote:
> > This allows specifying an IRQ source ID to be used when injecting an
> > interrupt.  When not specified KVM_USERSPACE_IRQ_SOURCE_ID is used.
> > 
> > Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> > ---
> > 
> >  Documentation/virtual/kvm/api.txt |    5 +++++
> >  arch/x86/kvm/x86.c                |    1 +
> >  include/linux/kvm.h               |    6 +++++-
> >  virt/kvm/eventfd.c                |   14 ++++++++++----
> >  4 files changed, 21 insertions(+), 5 deletions(-)
> > 
> > diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> > index 062cfd5..46f4b4d 100644
> > --- a/Documentation/virtual/kvm/api.txt
> > +++ b/Documentation/virtual/kvm/api.txt
> > @@ -1946,6 +1946,11 @@ the guest using the specified gsi pin.  The irqfd is removed using
> >  the KVM_IRQFD_FLAG_DEASSIGN flag, specifying both kvm_irqfd.fd
> >  and kvm_irqfd.gsi.
> >  
> > +When KVM_CAP_IRQFD_IRQ_SOURCE_ID is available, KVM_IRQFD supports the
> > +KVM_IRQFD_FLAG_IRQ_SOURCE_ID which can be used to specify an IRQ
> > +source ID (see KVM_IRQ_SOURCE_ID) to be used for the guest interrupt.
> > +This flag has no effect on deassignment.
> > +
> >  4.76 KVM_PPC_ALLOCATE_HTAB
> >  
> >  Capability: KVM_CAP_PPC_ALLOC_HTAB
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index 75e743e..946c5bd 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -2174,6 +2174,7 @@ int kvm_dev_ioctl_check_extension(long ext)
> >  	case KVM_CAP_GET_TSC_KHZ:
> >  	case KVM_CAP_PCI_2_3:
> >  	case KVM_CAP_KVMCLOCK_CTRL:
> > +	case KVM_CAP_IRQFD_IRQ_SOURCE_ID:
> >  		r = 1;
> >  		break;
> >  	case KVM_CAP_COALESCED_MMIO:
> > diff --git a/include/linux/kvm.h b/include/linux/kvm.h
> > index 67b6b49..deda8a9 100644
> > --- a/include/linux/kvm.h
> > +++ b/include/linux/kvm.h
> > @@ -619,6 +619,7 @@ struct kvm_ppc_smmu_info {
> >  #define KVM_CAP_S390_COW 79
> >  #define KVM_CAP_PPC_ALLOC_HTAB 80
> >  #define KVM_CAP_NR_IRQ_SOURCE_ID 81
> > +#define KVM_CAP_IRQFD_IRQ_SOURCE_ID 82
> >  
> >  #ifdef KVM_CAP_IRQ_ROUTING
> >  
> > @@ -684,12 +685,15 @@ struct kvm_xen_hvm_config {
> >  #endif
> >  
> >  #define KVM_IRQFD_FLAG_DEASSIGN (1 << 0)
> > +/* Available with KVM_CAP_IRQFD_IRQ_SOURCE_ID */
> > +#define KVM_IRQFD_FLAG_IRQ_SOURCE_ID (1 << 1)
> >  
> >  struct kvm_irqfd {
> >  	__u32 fd;
> >  	__u32 gsi;
> >  	__u32 flags;
> > -	__u8  pad[20];
> > +	__u32 irq_source_id;
> > +	__u8  pad[16];
> >  };
> >  
> >  #define KVM_IRQ_SOURCE_ID_FLAG_DEASSIGN (1 << 0)
> > diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
> > index 7d7e2aa..30150f1 100644
> > --- a/virt/kvm/eventfd.c
> > +++ b/virt/kvm/eventfd.c
> > @@ -51,6 +51,7 @@ struct _irqfd {
> >  	struct kvm_kernel_irq_routing_entry __rcu *irq_entry;
> >  	/* Used for level IRQ fast-path */
> >  	int gsi;
> > +	int irq_source_id;
> >  	struct work_struct inject;
> >  	/* Used for setup/shutdown */
> >  	struct eventfd_ctx *eventfd;
> > @@ -67,8 +68,8 @@ irqfd_inject(struct work_struct *work)
> >  	struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
> >  	struct kvm *kvm = irqfd->kvm;
> >  
> > -	kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1);
> > -	kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0);
> > +	kvm_set_irq(kvm, irqfd->irq_source_id, irqfd->gsi, 1);
> > +	kvm_set_irq(kvm, irqfd->irq_source_id, irqfd->gsi, 0);
> 
> Looks like this can lead to kernel data corruption if irq_source_id
> specified it out of range?

Yep, we need range checking and maybe even cross check against user
allocated IDs.

> >  }
> >  
> >  /*
> > @@ -138,7 +139,7 @@ irqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key)
> >  		irq = rcu_dereference(irqfd->irq_entry);
> >  		/* An event has been signaled, inject an interrupt */
> >  		if (irq)
> > -			kvm_set_msi(irq, kvm, KVM_USERSPACE_IRQ_SOURCE_ID, 1);
> > +			kvm_set_msi(irq, kvm, irqfd->irq_source_id, 1);
> >  		else
> >  			schedule_work(&irqfd->inject);
> >  		rcu_read_unlock();
> > @@ -213,6 +214,10 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
> >  
> >  	irqfd->kvm = kvm;
> >  	irqfd->gsi = args->gsi;
> > +	if (args->flags & KVM_IRQFD_FLAG_IRQ_SOURCE_ID)
> > +		irqfd->irq_source_id = args->irq_source_id;
> > +	else
> > +		irqfd->irq_source_id = KVM_USERSPACE_IRQ_SOURCE_ID;
> 
> As in the previous patch, there is no validation
> that source id was previously allocated to userspace, so this makes life
> harder for userspace: if it deassigns a used source ID the result is not
> a clean failure but hard to find bugs.

Yep, good point.  Some trivial bitmap management should fix this.

> >  	INIT_LIST_HEAD(&irqfd->list);
> >  	INIT_WORK(&irqfd->inject, irqfd_inject);
> >  	INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
> > @@ -340,7 +345,8 @@ kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
> >  int
> >  kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
> >  {
> > -	if (args->flags & ~KVM_IRQFD_FLAG_DEASSIGN)
> > +	if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN |
> > +			    KVM_IRQFD_FLAG_IRQ_SOURCE_ID))
> >  		return -EINVAL;
> >  
> >  	if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)

Summary:
      * user allocation bitmap needs to be cross-referenced by consumers
        of user passed source IDs.

Thanks,

Alex

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diff mbox

Patch

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 062cfd5..46f4b4d 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1946,6 +1946,11 @@  the guest using the specified gsi pin.  The irqfd is removed using
 the KVM_IRQFD_FLAG_DEASSIGN flag, specifying both kvm_irqfd.fd
 and kvm_irqfd.gsi.
 
+When KVM_CAP_IRQFD_IRQ_SOURCE_ID is available, KVM_IRQFD supports the
+KVM_IRQFD_FLAG_IRQ_SOURCE_ID which can be used to specify an IRQ
+source ID (see KVM_IRQ_SOURCE_ID) to be used for the guest interrupt.
+This flag has no effect on deassignment.
+
 4.76 KVM_PPC_ALLOCATE_HTAB
 
 Capability: KVM_CAP_PPC_ALLOC_HTAB
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 75e743e..946c5bd 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2174,6 +2174,7 @@  int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_GET_TSC_KHZ:
 	case KVM_CAP_PCI_2_3:
 	case KVM_CAP_KVMCLOCK_CTRL:
+	case KVM_CAP_IRQFD_IRQ_SOURCE_ID:
 		r = 1;
 		break;
 	case KVM_CAP_COALESCED_MMIO:
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 67b6b49..deda8a9 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -619,6 +619,7 @@  struct kvm_ppc_smmu_info {
 #define KVM_CAP_S390_COW 79
 #define KVM_CAP_PPC_ALLOC_HTAB 80
 #define KVM_CAP_NR_IRQ_SOURCE_ID 81
+#define KVM_CAP_IRQFD_IRQ_SOURCE_ID 82
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -684,12 +685,15 @@  struct kvm_xen_hvm_config {
 #endif
 
 #define KVM_IRQFD_FLAG_DEASSIGN (1 << 0)
+/* Available with KVM_CAP_IRQFD_IRQ_SOURCE_ID */
+#define KVM_IRQFD_FLAG_IRQ_SOURCE_ID (1 << 1)
 
 struct kvm_irqfd {
 	__u32 fd;
 	__u32 gsi;
 	__u32 flags;
-	__u8  pad[20];
+	__u32 irq_source_id;
+	__u8  pad[16];
 };
 
 #define KVM_IRQ_SOURCE_ID_FLAG_DEASSIGN (1 << 0)
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 7d7e2aa..30150f1 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -51,6 +51,7 @@  struct _irqfd {
 	struct kvm_kernel_irq_routing_entry __rcu *irq_entry;
 	/* Used for level IRQ fast-path */
 	int gsi;
+	int irq_source_id;
 	struct work_struct inject;
 	/* Used for setup/shutdown */
 	struct eventfd_ctx *eventfd;
@@ -67,8 +68,8 @@  irqfd_inject(struct work_struct *work)
 	struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
 	struct kvm *kvm = irqfd->kvm;
 
-	kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1);
-	kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0);
+	kvm_set_irq(kvm, irqfd->irq_source_id, irqfd->gsi, 1);
+	kvm_set_irq(kvm, irqfd->irq_source_id, irqfd->gsi, 0);
 }
 
 /*
@@ -138,7 +139,7 @@  irqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key)
 		irq = rcu_dereference(irqfd->irq_entry);
 		/* An event has been signaled, inject an interrupt */
 		if (irq)
-			kvm_set_msi(irq, kvm, KVM_USERSPACE_IRQ_SOURCE_ID, 1);
+			kvm_set_msi(irq, kvm, irqfd->irq_source_id, 1);
 		else
 			schedule_work(&irqfd->inject);
 		rcu_read_unlock();
@@ -213,6 +214,10 @@  kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
 
 	irqfd->kvm = kvm;
 	irqfd->gsi = args->gsi;
+	if (args->flags & KVM_IRQFD_FLAG_IRQ_SOURCE_ID)
+		irqfd->irq_source_id = args->irq_source_id;
+	else
+		irqfd->irq_source_id = KVM_USERSPACE_IRQ_SOURCE_ID;
 	INIT_LIST_HEAD(&irqfd->list);
 	INIT_WORK(&irqfd->inject, irqfd_inject);
 	INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
@@ -340,7 +345,8 @@  kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
 int
 kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
 {
-	if (args->flags & ~KVM_IRQFD_FLAG_DEASSIGN)
+	if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN |
+			    KVM_IRQFD_FLAG_IRQ_SOURCE_ID))
 		return -EINVAL;
 
 	if (args->flags & KVM_IRQFD_FLAG_DEASSIGN)