diff mbox series

[v4,2/6] vhost: Simplify ring verification checks

Message ID 20171213180807.7066-3-dgilbert@redhat.com
State New
Headers show
Series Rework vhost memory region updates | expand

Commit Message

Dr. David Alan Gilbert Dec. 13, 2017, 6:08 p.m. UTC 
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

vhost_verify_ring_mappings() were used to verify that
rings are still accessible and related memory hasn't
been moved after flatview is updated.

It was doing checks by mapping ring's GPA+len and
checking that HVA hadn't changed with new memory map.
To avoid maybe expensive mapping call, we were
identifying address range that changed and were doing
mapping only if ring was in changed range.

However it's not neccessary to perform ring's GPA
mapping as we already have its current HVA and all
we need is to verify that ring's GPA translates to
the same HVA in updated flatview.

This will allow the following patches to simplify the range
comparison that was previously needed to avoid expensive
verify_ring_mapping calls.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
with modifications by:
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 hw/virtio/vhost.c | 74 ++++++++++++++++++++++++++++++-------------------------
 1 file changed, 41 insertions(+), 33 deletions(-)

Comments

Igor Mammedov Dec. 14, 2017, 2:07 p.m. UTC | #1 
On Wed, 13 Dec 2017 18:08:03 +0000
"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:

> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> vhost_verify_ring_mappings() were used to verify that
> rings are still accessible and related memory hasn't
> been moved after flatview is updated.
> 
> It was doing checks by mapping ring's GPA+len and
> checking that HVA hadn't changed with new memory map.
> To avoid maybe expensive mapping call, we were
> identifying address range that changed and were doing
> mapping only if ring was in changed range.
> 
> However it's not neccessary to perform ring's GPA
> mapping as we already have its current HVA and all
> we need is to verify that ring's GPA translates to
> the same HVA in updated flatview.
> 
> This will allow the following patches to simplify the range
> comparison that was previously needed to avoid expensive
> verify_ring_mapping calls.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> with modifications by:
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
>  hw/virtio/vhost.c | 74 ++++++++++++++++++++++++++++++-------------------------
>  1 file changed, 41 insertions(+), 33 deletions(-)
> 
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index e923219e63..c7ce7baf9b 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -450,35 +450,37 @@ static void vhost_memory_unmap(struct vhost_dev *dev, void *buffer,
>      }
>  }
>  
> -static int vhost_verify_ring_part_mapping(struct vhost_dev *dev,
> -                                          void *part,
> -                                          uint64_t part_addr,
> -                                          uint64_t part_size,
> -                                          uint64_t start_addr,
> -                                          uint64_t size)
> +static int vhost_verify_ring_part_mapping(void *ring_hva,
> +                                          uint64_t ring_gpa,
> +                                          uint64_t ring_size,
> +                                          void *reg_hva,
> +                                          uint64_t reg_gpa,
> +                                          uint64_t reg_size)
>  {
> -    hwaddr l;
> -    void *p;
> -    int r = 0;
> +    uint64_t hva_ring_offset;
> +    uint64_t ring_last = range_get_last(ring_gpa, ring_size);
> +    uint64_t reg_last = range_get_last(reg_gpa, reg_size);
>  
> -    if (!ranges_overlap(start_addr, size, part_addr, part_size)) {
> +    if (ring_last < reg_gpa || ring_gpa > reg_last) {
>          return 0;
>      }
> -    l = part_size;
> -    p = vhost_memory_map(dev, part_addr, &l, 1);
> -    if (!p || l != part_size) {
> -        r = -ENOMEM;
> +    /* check that whole ring's is mapped */
> +    if (ring_last > reg_last) {
> +        return -EBUSY;
ENOMEM

>      }
> -    if (p != part) {
> -        r = -EBUSY;
> +    /* check that ring's MemoryRegion wasn't replaced */
> +    hva_ring_offset = ring_gpa - reg_gpa;
> +    if (ring_hva != reg_hva + hva_ring_offset) {
> +        return -ENOMEM;
EBUSY

>      }
> -    vhost_memory_unmap(dev, p, l, 0, 0);
> -    return r;
> +
> +    return 0;
>  }
>  
>  static int vhost_verify_ring_mappings(struct vhost_dev *dev,
> -                                      uint64_t start_addr,
> -                                      uint64_t size)
> +                                      void *reg_hva,
> +                                      uint64_t reg_gpa,
> +                                      uint64_t reg_size)
>  {
>      int i, j;
>      int r = 0;
> @@ -492,22 +494,25 @@ static int vhost_verify_ring_mappings(struct vhost_dev *dev,
>          struct vhost_virtqueue *vq = dev->vqs + i;
>  
>          j = 0;
> -        r = vhost_verify_ring_part_mapping(dev, vq->desc, vq->desc_phys,
> -                                           vq->desc_size, start_addr, size);
> +        r = vhost_verify_ring_part_mapping(
> +                vq->desc, vq->desc_phys, vq->desc_size,
> +                reg_hva, reg_gpa, reg_size);
>          if (r) {
>              break;
>          }
>  
>          j++;
> -        r = vhost_verify_ring_part_mapping(dev, vq->avail, vq->avail_phys,
> -                                           vq->avail_size, start_addr, size);
> +        r = vhost_verify_ring_part_mapping(
> +                vq->desc, vq->desc_phys, vq->desc_size,
> +                reg_hva, reg_gpa, reg_size);
>          if (r) {
>              break;
>          }
>  
>          j++;
> -        r = vhost_verify_ring_part_mapping(dev, vq->used, vq->used_phys,
> -                                           vq->used_size, start_addr, size);
> +        r = vhost_verify_ring_part_mapping(
> +                vq->desc, vq->desc_phys, vq->desc_size,
> +                reg_hva, reg_gpa, reg_size);
>          if (r) {
>              break;
>          }
> @@ -633,8 +638,6 @@ static void vhost_commit(MemoryListener *listener)
>  {
>      struct vhost_dev *dev = container_of(listener, struct vhost_dev,
>                                           memory_listener);
> -    hwaddr start_addr = 0;
> -    ram_addr_t size = 0;
>      uint64_t log_size;
>      int r;
>  
> @@ -649,11 +652,16 @@ static void vhost_commit(MemoryListener *listener)
>      }
>  
>      if (dev->started) {
^^^ not needed as we bail out earlier if it's not true

> -        start_addr = dev->mem_changed_start_addr;
> -        size = dev->mem_changed_end_addr - dev->mem_changed_start_addr + 1;
> -
> -        r = vhost_verify_ring_mappings(dev, start_addr, size);
> -        assert(r >= 0);
> +        int i;
> +        for (i = 0; i < dev->mem->nregions; i++) {
> +            if (vhost_verify_ring_mappings(dev,
> +                               (void *)dev->mem->regions[i].userspace_addr,
> +                               dev->mem->regions[i].guest_phys_addr,
> +                               dev->mem->regions[i].memory_size)) {
> +                error_report("Verify ring failure on region %d", i);
> +                abort();
> +            }
> +        }
>      }
>  
>      if (!dev->log_enabled) {
Dr. David Alan Gilbert Dec. 15, 2017, 12:24 p.m. UTC | #2 
* Igor Mammedov (imammedo@redhat.com) wrote:
> On Wed, 13 Dec 2017 18:08:03 +0000
> "Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:
> 
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > 
> > vhost_verify_ring_mappings() were used to verify that
> > rings are still accessible and related memory hasn't
> > been moved after flatview is updated.
> > 
> > It was doing checks by mapping ring's GPA+len and
> > checking that HVA hadn't changed with new memory map.
> > To avoid maybe expensive mapping call, we were
> > identifying address range that changed and were doing
> > mapping only if ring was in changed range.
> > 
> > However it's not neccessary to perform ring's GPA
> > mapping as we already have its current HVA and all
> > we need is to verify that ring's GPA translates to
> > the same HVA in updated flatview.
> > 
> > This will allow the following patches to simplify the range
> > comparison that was previously needed to avoid expensive
> > verify_ring_mapping calls.
> > 
> > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > with modifications by:
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > ---
> >  hw/virtio/vhost.c | 74 ++++++++++++++++++++++++++++++-------------------------
> >  1 file changed, 41 insertions(+), 33 deletions(-)
> > 
> > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> > index e923219e63..c7ce7baf9b 100644
> > --- a/hw/virtio/vhost.c
> > +++ b/hw/virtio/vhost.c
> > @@ -450,35 +450,37 @@ static void vhost_memory_unmap(struct vhost_dev *dev, void *buffer,
> >      }
> >  }
> >  
> > -static int vhost_verify_ring_part_mapping(struct vhost_dev *dev,
> > -                                          void *part,
> > -                                          uint64_t part_addr,
> > -                                          uint64_t part_size,
> > -                                          uint64_t start_addr,
> > -                                          uint64_t size)
> > +static int vhost_verify_ring_part_mapping(void *ring_hva,
> > +                                          uint64_t ring_gpa,
> > +                                          uint64_t ring_size,
> > +                                          void *reg_hva,
> > +                                          uint64_t reg_gpa,
> > +                                          uint64_t reg_size)
> >  {
> > -    hwaddr l;
> > -    void *p;
> > -    int r = 0;
> > +    uint64_t hva_ring_offset;
> > +    uint64_t ring_last = range_get_last(ring_gpa, ring_size);
> > +    uint64_t reg_last = range_get_last(reg_gpa, reg_size);
> >  
> > -    if (!ranges_overlap(start_addr, size, part_addr, part_size)) {
> > +    if (ring_last < reg_gpa || ring_gpa > reg_last) {
> >          return 0;
> >      }
> > -    l = part_size;
> > -    p = vhost_memory_map(dev, part_addr, &l, 1);
> > -    if (!p || l != part_size) {
> > -        r = -ENOMEM;
> > +    /* check that whole ring's is mapped */
> > +    if (ring_last > reg_last) {
> > +        return -EBUSY;
> ENOMEM

Done

> >      }
> > -    if (p != part) {
> > -        r = -EBUSY;
> > +    /* check that ring's MemoryRegion wasn't replaced */
> > +    hva_ring_offset = ring_gpa - reg_gpa;
> > +    if (ring_hva != reg_hva + hva_ring_offset) {
> > +        return -ENOMEM;
> EBUSY

Done

> 
> >      }
> > -    vhost_memory_unmap(dev, p, l, 0, 0);
> > -    return r;
> > +
> > +    return 0;
> >  }
> >  
> >  static int vhost_verify_ring_mappings(struct vhost_dev *dev,
> > -                                      uint64_t start_addr,
> > -                                      uint64_t size)
> > +                                      void *reg_hva,
> > +                                      uint64_t reg_gpa,
> > +                                      uint64_t reg_size)
> >  {
> >      int i, j;
> >      int r = 0;
> > @@ -492,22 +494,25 @@ static int vhost_verify_ring_mappings(struct vhost_dev *dev,
> >          struct vhost_virtqueue *vq = dev->vqs + i;
> >  
> >          j = 0;
> > -        r = vhost_verify_ring_part_mapping(dev, vq->desc, vq->desc_phys,
> > -                                           vq->desc_size, start_addr, size);
> > +        r = vhost_verify_ring_part_mapping(
> > +                vq->desc, vq->desc_phys, vq->desc_size,
> > +                reg_hva, reg_gpa, reg_size);
> >          if (r) {
> >              break;
> >          }
> >  
> >          j++;
> > -        r = vhost_verify_ring_part_mapping(dev, vq->avail, vq->avail_phys,
> > -                                           vq->avail_size, start_addr, size);
> > +        r = vhost_verify_ring_part_mapping(
> > +                vq->desc, vq->desc_phys, vq->desc_size,
> > +                reg_hva, reg_gpa, reg_size);
> >          if (r) {
> >              break;
> >          }
> >  
> >          j++;
> > -        r = vhost_verify_ring_part_mapping(dev, vq->used, vq->used_phys,
> > -                                           vq->used_size, start_addr, size);
> > +        r = vhost_verify_ring_part_mapping(
> > +                vq->desc, vq->desc_phys, vq->desc_size,
> > +                reg_hva, reg_gpa, reg_size);
> >          if (r) {
> >              break;
> >          }
> > @@ -633,8 +638,6 @@ static void vhost_commit(MemoryListener *listener)
> >  {
> >      struct vhost_dev *dev = container_of(listener, struct vhost_dev,
> >                                           memory_listener);
> > -    hwaddr start_addr = 0;
> > -    ram_addr_t size = 0;
> >      uint64_t log_size;
> >      int r;
> >  
> > @@ -649,11 +652,16 @@ static void vhost_commit(MemoryListener *listener)
> >      }
> >  
> >      if (dev->started) {
> ^^^ not needed as we bail out earlier if it's not true

Done

> > -        start_addr = dev->mem_changed_start_addr;
> > -        size = dev->mem_changed_end_addr - dev->mem_changed_start_addr + 1;
> > -
> > -        r = vhost_verify_ring_mappings(dev, start_addr, size);
> > -        assert(r >= 0);
> > +        int i;
> > +        for (i = 0; i < dev->mem->nregions; i++) {
> > +            if (vhost_verify_ring_mappings(dev,
> > +                               (void *)dev->mem->regions[i].userspace_addr,
> > +                               dev->mem->regions[i].guest_phys_addr,
> > +                               dev->mem->regions[i].memory_size)) {
> > +                error_report("Verify ring failure on region %d", i);
> > +                abort();
> > +            }
> > +        }
> >      }
> >  
> >      if (!dev->log_enabled) {
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
diff mbox series

Patch

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index e923219e63..c7ce7baf9b 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -450,35 +450,37 @@  static void vhost_memory_unmap(struct vhost_dev *dev, void *buffer,
     }
 }
 
-static int vhost_verify_ring_part_mapping(struct vhost_dev *dev,
-                                          void *part,
-                                          uint64_t part_addr,
-                                          uint64_t part_size,
-                                          uint64_t start_addr,
-                                          uint64_t size)
+static int vhost_verify_ring_part_mapping(void *ring_hva,
+                                          uint64_t ring_gpa,
+                                          uint64_t ring_size,
+                                          void *reg_hva,
+                                          uint64_t reg_gpa,
+                                          uint64_t reg_size)
 {
-    hwaddr l;
-    void *p;
-    int r = 0;
+    uint64_t hva_ring_offset;
+    uint64_t ring_last = range_get_last(ring_gpa, ring_size);
+    uint64_t reg_last = range_get_last(reg_gpa, reg_size);
 
-    if (!ranges_overlap(start_addr, size, part_addr, part_size)) {
+    if (ring_last < reg_gpa || ring_gpa > reg_last) {
         return 0;
     }
-    l = part_size;
-    p = vhost_memory_map(dev, part_addr, &l, 1);
-    if (!p || l != part_size) {
-        r = -ENOMEM;
+    /* check that whole ring's is mapped */
+    if (ring_last > reg_last) {
+        return -EBUSY;
     }
-    if (p != part) {
-        r = -EBUSY;
+    /* check that ring's MemoryRegion wasn't replaced */
+    hva_ring_offset = ring_gpa - reg_gpa;
+    if (ring_hva != reg_hva + hva_ring_offset) {
+        return -ENOMEM;
     }
-    vhost_memory_unmap(dev, p, l, 0, 0);
-    return r;
+
+    return 0;
 }
 
 static int vhost_verify_ring_mappings(struct vhost_dev *dev,
-                                      uint64_t start_addr,
-                                      uint64_t size)
+                                      void *reg_hva,
+                                      uint64_t reg_gpa,
+                                      uint64_t reg_size)
 {
     int i, j;
     int r = 0;
@@ -492,22 +494,25 @@  static int vhost_verify_ring_mappings(struct vhost_dev *dev,
         struct vhost_virtqueue *vq = dev->vqs + i;
 
         j = 0;
-        r = vhost_verify_ring_part_mapping(dev, vq->desc, vq->desc_phys,
-                                           vq->desc_size, start_addr, size);
+        r = vhost_verify_ring_part_mapping(
+                vq->desc, vq->desc_phys, vq->desc_size,
+                reg_hva, reg_gpa, reg_size);
         if (r) {
             break;
         }
 
         j++;
-        r = vhost_verify_ring_part_mapping(dev, vq->avail, vq->avail_phys,
-                                           vq->avail_size, start_addr, size);
+        r = vhost_verify_ring_part_mapping(
+                vq->desc, vq->desc_phys, vq->desc_size,
+                reg_hva, reg_gpa, reg_size);
         if (r) {
             break;
         }
 
         j++;
-        r = vhost_verify_ring_part_mapping(dev, vq->used, vq->used_phys,
-                                           vq->used_size, start_addr, size);
+        r = vhost_verify_ring_part_mapping(
+                vq->desc, vq->desc_phys, vq->desc_size,
+                reg_hva, reg_gpa, reg_size);
         if (r) {
             break;
         }
@@ -633,8 +638,6 @@  static void vhost_commit(MemoryListener *listener)
 {
     struct vhost_dev *dev = container_of(listener, struct vhost_dev,
                                          memory_listener);
-    hwaddr start_addr = 0;
-    ram_addr_t size = 0;
     uint64_t log_size;
     int r;
 
@@ -649,11 +652,16 @@  static void vhost_commit(MemoryListener *listener)
     }
 
     if (dev->started) {
-        start_addr = dev->mem_changed_start_addr;
-        size = dev->mem_changed_end_addr - dev->mem_changed_start_addr + 1;
-
-        r = vhost_verify_ring_mappings(dev, start_addr, size);
-        assert(r >= 0);
+        int i;
+        for (i = 0; i < dev->mem->nregions; i++) {
+            if (vhost_verify_ring_mappings(dev,
+                               (void *)dev->mem->regions[i].userspace_addr,
+                               dev->mem->regions[i].guest_phys_addr,
+                               dev->mem->regions[i].memory_size)) {
+                error_report("Verify ring failure on region %d", i);
+                abort();
+            }
+        }
     }
 
     if (!dev->log_enabled) {