qemu-kvm/vhost: fix up irqfd support

vhost irqfd support: case where many vqs are mapped to a single msix vector is currently broken. Fix it up.

Signed-off-by Michael S. Tsirkin <[email protected]>

---

This is on top of the qemu patchset, which is unchanged. Fixes from v1:
correct error handling

 hw/msix.c       |   68 ++++++++++++++++++++++++++++++++++++++-----------------
 hw/msix.h       |    4 +-
 hw/pci.h        |    3 +-
 hw/virtio-pci.c |   56 ++++++++++++++++++++++++++++++++++++++-------
 4 files changed, 97 insertions(+), 34 deletions(-)

hw/msix.c +5 -19

index 3dd0456..3d4dd61 100644
@@ -300,10 +300,8 @@ static void msix_mmio_writel(void *opaque, target_phys_addr_t addr,
     if (kvm_enabled() && kvm_irqchip_in_kernel()) {
         kvm_msix_update(dev, vector, was_masked, msix_is_masked(dev, vector));
     }
-    if (was_masked != msix_is_masked(dev, vector) &&
-        dev->msix_mask_notifier && dev->msix_mask_notifier_opaque[vector]) {
+    if (was_masked != msix_is_masked(dev, vector) && dev->msix_mask_notifier) {
         int r = dev->msix_mask_notifier(dev, vector,
-					dev->msix_mask_notifier_opaque[vector],
 					msix_is_masked(dev, vector));
         assert(r >= 0);
     }

@@ -351,9 +349,8 @@ static void msix_mask_all(struct PCIDevice *dev, unsigned nentries)
         int was_masked = msix_is_masked(dev, vector);
         dev->msix_table_page[offset] |= MSIX_VECTOR_MASK;
         if (was_masked != msix_is_masked(dev, vector) &&
-            dev->msix_mask_notifier && dev->msix_mask_notifier_opaque[vector]) {
+            dev->msix_mask_notifier) {
             r = dev->msix_mask_notifier(dev, vector,
-                                        dev->msix_mask_notifier_opaque[vector],
                                         msix_is_masked(dev, vector));
             assert(r >= 0);
         }

@@ -379,8 +376,6 @@ int msix_init(struct PCIDevice *dev, unsigned short nentries,
                                             sizeof *dev->msix_irq_entries);
     }
 #endif
-    dev->msix_mask_notifier_opaque =
-        qemu_mallocz(nentries * sizeof *dev->msix_mask_notifier_opaque);
     dev->msix_mask_notifier = NULL;
     dev->msix_entry_used = qemu_mallocz(MSIX_MAX_ENTRIES *
                                         sizeof *dev->msix_entry_used);

@@ -444,8 +439,6 @@ int msix_uninit(PCIDevice *dev)
     dev->msix_entry_used = NULL;
     qemu_free(dev->msix_irq_entries);
     dev->msix_irq_entries = NULL;
-    qemu_free(dev->msix_mask_notifier_opaque);
-    dev->msix_mask_notifier_opaque = NULL;
     dev->cap_present &= ~QEMU_PCI_CAP_MSIX;
     return 0;
 }

@@ -590,46 +583,79 @@ void msix_unuse_all_vectors(PCIDevice *dev)
     msix_free_irq_entries(dev);
 }
 
-int msix_set_mask_notifier(PCIDevice *dev, unsigned vector, void *opaque)
+static int msix_set_mask_notifier_for_vector(PCIDevice *dev, unsigned vector)
 {
     int r = 0;
     if (vector >= dev->msix_entries_nr || !dev->msix_entry_used[vector])
         return 0;
 
     assert(dev->msix_mask_notifier);
-    assert(opaque);
-    assert(!dev->msix_mask_notifier_opaque[vector]);
 
     /* Unmask the new notifier unless vector is masked. */
     if (!msix_is_masked(dev, vector)) {
-        r = dev->msix_mask_notifier(dev, vector, opaque, false);
+        r = dev->msix_mask_notifier(dev, vector, false);
         if (r < 0) {
             return r;
         }
     }
-    dev->msix_mask_notifier_opaque[vector] = opaque;
     return r;
 }
 
-int msix_unset_mask_notifier(PCIDevice *dev, unsigned vector)
+static int msix_unset_mask_notifier_for_vector(PCIDevice *dev, unsigned vector)
 {
     int r = 0;
-    void *opaque;
     if (vector >= dev->msix_entries_nr || !dev->msix_entry_used[vector])
         return 0;
 
-    opaque = dev->msix_mask_notifier_opaque[vector];
-
     assert(dev->msix_mask_notifier);
-    assert(opaque);
 
     /* Mask the old notifier unless it is already masked. */

hw/msix.c +39 -0

+
+int msix_set_mask_notifier(PCIDevice *dev, msix_mask_notifier_func f)
+{
+    int r, n;
+    assert(!dev->msix_mask_notifier);
+    dev->msix_mask_notifier = f;
+    for (n = 0; n < dev->msix_entries_nr; ++n) {
+        r = msix_set_mask_notifier_for_vector(dev, n);
+        if (r < 0) {
+            goto undo;
+        }
+    }
+    return 0;
+
+undo:
+    while (--n >= 0) {
+        msix_unset_mask_notifier_for_vector(dev, n);
+    }
+    dev->msix_mask_notifier = NULL;
+    return r;
+}
+
+int msix_unset_mask_notifier(PCIDevice *dev)
+{
+    int r, n;
+    assert(dev->msix_mask_notifier);
+    for (n = 0; n < dev->msix_entries_nr; ++n) {
+        r = msix_unset_mask_notifier_for_vector(dev, n);
+        if (r < 0) {
+            goto undo;
+        }
+    }
+    dev->msix_mask_notifier = NULL;
+    return 0;
+
+undo:
+    while (--n >= 0) {
+        msix_set_mask_notifier_for_vector(dev, n);
+    }
     return r;
 }

hw/msix.h +2 -2

index 6b21ffb..5a81df5 100644
@@ -33,6 +33,6 @@ void msix_reset(PCIDevice *dev);
 
 extern int msix_supported;
 
-int msix_set_mask_notifier(PCIDevice *dev, unsigned vector, void *opaque);
-int msix_unset_mask_notifier(PCIDevice *dev, unsigned vector);
+int msix_set_mask_notifier(PCIDevice *dev, msix_mask_notifier_func);
+int msix_unset_mask_notifier(PCIDevice *dev);
 #endif

hw/pci.h +1 -2

index ccb99d0..a40dc14 100644
@@ -131,7 +131,7 @@ enum {
 #define PCI_CAPABILITY_CONFIG_MSIX_LENGTH 0x10
 
 typedef int (*msix_mask_notifier_func)(PCIDevice *, unsigned vector,
-				       void *opaque, int masked);
+				       int masked);
 
 struct PCIDevice {
     DeviceState qdev;

@@ -198,7 +198,6 @@ struct PCIDevice {
 
     struct kvm_irq_routing_entry *msix_irq_entries;
 
-    void **msix_mask_notifier_opaque;
     msix_mask_notifier_func msix_mask_notifier;
 
     /* Device capability configuration space */

hw/virtio-pci.c +47 -9

index 232f943..c1204ce 100644
@@ -428,11 +428,10 @@ static void virtio_pci_guest_notifier_read(void *opaque)
     }
 }
 
-static int virtio_pci_mask_notifier(PCIDevice *dev, unsigned vector,
-                                    void *opaque, int masked)
+static int virtio_pci_mask_vq(PCIDevice *dev, unsigned vector,
+                              VirtQueue *vq, int masked)
 {
 #ifdef CONFIG_KVM
-    VirtQueue *vq = opaque;
     EventNotifier *notifier = virtio_queue_get_guest_notifier(vq);
     int r = kvm_set_irqfd(dev->msix_irq_entries[vector].gsi,
                           event_notifier_get_fd(notifier),

@@ -453,6 +452,34 @@ static int virtio_pci_mask_notifier(PCIDevice *dev, unsigned vector,
 #endif
 }
 
+static int virtio_pci_mask_notifier(PCIDevice *dev, unsigned vector,
+                                    int masked)
+{
+    VirtIOPCIProxy *proxy = container_of(dev, VirtIOPCIProxy, pci_dev);
+    VirtIODevice *vdev = proxy->vdev;
+    int r, n;
+
+    for (n = 0; n < VIRTIO_PCI_QUEUE_MAX; n++) {
+        if (!virtio_queue_get_num(vdev, n)) {
+            break;
+        }
+        if (virtio_queue_vector(vdev, n) != vector) {
+            continue;
+        }
+        r = virtio_pci_mask_vq(dev, vector, virtio_get_queue(vdev, n), masked);
+        if (r < 0) {
+            goto undo;
+        }
+    }
+    return 0;
+undo:
+    while (--n >= 0) {
+        virtio_pci_mask_vq(dev, vector, virtio_get_queue(vdev, n), !masked);
+    }
+    return r;
+}
+
+
 static int virtio_pci_set_guest_notifier(void *opaque, int n, bool assign)
 {
     VirtIOPCIProxy *proxy = opaque;

@@ -466,11 +493,7 @@ static int virtio_pci_set_guest_notifier(void *opaque, int n, bool assign)
         }
         qemu_set_fd_handler(event_notifier_get_fd(notifier),
                             virtio_pci_guest_notifier_read, NULL, vq);
-        msix_set_mask_notifier(&proxy->pci_dev,
-                               virtio_queue_vector(proxy->vdev, n), vq);
     } else {
-        msix_unset_mask_notifier(&proxy->pci_dev,
-				 virtio_queue_vector(proxy->vdev, n));
         qemu_set_fd_handler(event_notifier_get_fd(notifier),
                             NULL, NULL, NULL);
         /* Test and clear notifier before closing it,

@@ -488,6 +511,13 @@ static int virtio_pci_set_guest_notifiers(void *opaque, bool assign)
     VirtIODevice *vdev = proxy->vdev;
     int r, n;
 
+    /* Must unset mask notifier while guest notifier
+     * is still assigned */
+    if (!assign) {
+	    r = msix_unset_mask_notifier(&proxy->pci_dev);
+            assert(r >= 0);
+    }
+
     for (n = 0; n < VIRTIO_PCI_QUEUE_MAX; n++) {
         if (!virtio_queue_get_num(vdev, n)) {
             break;

@@ -499,6 +529,16 @@ static int virtio_pci_set_guest_notifiers(void *opaque, bool assign)
         }
     }
 
+    /* Must set mask notifier after guest notifier
+     * has been assigned */
+    if (assign) {
+        r = msix_set_mask_notifier(&proxy->pci_dev,
+                                   virtio_pci_mask_notifier);
+        if (r < 0) {
+            goto assign_error;
+        }
+    }
+
     return 0;
 
 assign_error:

@@ -584,8 +624,6 @@ static void virtio_init_pci(VirtIOPCIProxy *proxy, VirtIODevice *vdev,
 
     proxy->pci_dev.config_write = virtio_write_config;
 
-    proxy->pci_dev.msix_mask_notifier = virtio_pci_mask_notifier;
-
     size = VIRTIO_PCI_REGION_SIZE(&proxy->pci_dev) + vdev->config_len;
     if (size & (size-1))
         size = 1 << qemu_fls(size);

Quoted 14 lines

hw/msix.c +1 -5

-int msix_unset_mask_notifier(PCIDevice *dev, unsigned vector)
+static int msix_unset_mask_notifier_for_vector(PCIDevice *dev, unsigned vector)
 {
     int r = 0;
-    void *opaque;
     if (vector >= dev->msix_entries_nr || !dev->msix_entry_used[vector])
         return 0;
 
-    opaque = dev->msix_mask_notifier_opaque[vector];
-
     assert(dev->msix_mask_notifier);
-    assert(opaque);
 
     /* Mask the old notifier unless it is already masked. */

hw/msix.c void msix_unuse_all_vectors(PCIDevice *dev) · line 620

Quoted 10 lines

hw/msix.c +3 -2

     if (!msix_is_masked(dev, vector)) {
-        r = dev->msix_mask_notifier(dev, vector, opaque, true);
+        r = dev->msix_mask_notifier(dev, vector, true);
         if (r < 0) {
             return r;
         }
     }
-    dev->msix_mask_notifier_opaque[vector] = NULL;
+    return r;
+}

The above need to be combined to a single function now since the only difference is s/true/false.

Alex

Quoted 28 lines · Alex Williamson

Quoted 14 lines

hw/msix.c +1 -5

-int msix_unset_mask_notifier(PCIDevice *dev, unsigned vector)
+static int msix_unset_mask_notifier_for_vector(PCIDevice *dev, unsigned vector)
 {
     int r = 0;
-    void *opaque;
     if (vector >= dev->msix_entries_nr || !dev->msix_entry_used[vector])
         return 0;
 
-    opaque = dev->msix_mask_notifier_opaque[vector];
-
     assert(dev->msix_mask_notifier);
-    assert(opaque);
 
     /* Mask the old notifier unless it is already masked. */

hw/msix.c void msix_unuse_all_vectors(PCIDevice *dev) · line 620

Quoted 10 lines

hw/msix.c +3 -2

     if (!msix_is_masked(dev, vector)) {
-        r = dev->msix_mask_notifier(dev, vector, opaque, true);
+        r = dev->msix_mask_notifier(dev, vector, true);
         if (r < 0) {
             return r;
         }
     }
-    dev->msix_mask_notifier_opaque[vector] = NULL;
+    return r;
+}

The above need to be combined to a single function now since the only difference is s/true/false.

Quoted 1 line

Alex

This is the way it was in the past, and it turned out to be very confusing to read since both variables: mask and assign are bool but polarity is reversed.

Unrolled it seems easier to grok.

Quoted 35 lines · Michael S. Tsirkin

Quoted 28 lines · Alex Williamson

Quoted 14 lines

hw/msix.c +1 -5

-int msix_unset_mask_notifier(PCIDevice *dev, unsigned vector)
+static int msix_unset_mask_notifier_for_vector(PCIDevice *dev, unsigned vector)
 {
     int r = 0;
-    void *opaque;
     if (vector >= dev->msix_entries_nr || !dev->msix_entry_used[vector])
         return 0;
 
-    opaque = dev->msix_mask_notifier_opaque[vector];
-
     assert(dev->msix_mask_notifier);
-    assert(opaque);
 
     /* Mask the old notifier unless it is already masked. */

hw/msix.c void msix_unuse_all_vectors(PCIDevice *dev) · line 620

Quoted 10 lines

hw/msix.c +3 -2

     if (!msix_is_masked(dev, vector)) {
-        r = dev->msix_mask_notifier(dev, vector, opaque, true);
+        r = dev->msix_mask_notifier(dev, vector, true);
         if (r < 0) {
             return r;
         }
     }
-    dev->msix_mask_notifier_opaque[vector] = NULL;
+    return r;
+}

The above need to be combined to a single function now since the only difference is s/true/false.

Quoted 1 line

Alex

This is the way it was in the past, and it turned out to be very confusing to read since both variables: mask and assign are bool but polarity is reversed.

Quoted 1 line

Unrolled it seems easier to grok.

You could always keep the functions as separate wrapper callers of the common function so you only need to keep true = unset, false = set straight in one place. Thanks,

Alex

You could always keep the functions as separate wrapper callers of the common function so you only need to keep true = unset, false = set straight in one place. Thanks,

Quoted 3 lines · Alex Williamson

You could always keep the functions as separate wrapper callers of the common function so you only need to keep true = unset, false = set straight in one place. Thanks,

Just to show why it does not work, I did exactly this: as you see the code is shorter but the true/false magic gets spread: it was in 2 places, (set/unset) now it is in 4 places and it is within the loop, in code that is more complex.

So I think I'll stick to the original version and we can patch it up later if there's a will.

hw/msix.c +8 -34

index 3d4dd61..4b705a0 100644
@@ -583,40 +583,15 @@ void msix_unuse_all_vectors(PCIDevice *dev)
     msix_free_irq_entries(dev);
 }
 
-static int msix_set_mask_notifier_for_vector(PCIDevice *dev, unsigned vector)
+/* Invoke the notifier if vector entry is used and unmasked. */
+static int msix_notify_if_unmasked(PCIDevice *dev, unsigned vector, bool masked)
 {
     int r = 0;
-    if (vector >= dev->msix_entries_nr || !dev->msix_entry_used[vector])
+    if (!dev->msix_entry_used[vector] || msix_is_masked(dev, vector)) {
         return 0;
-
-    assert(dev->msix_mask_notifier);
-
-    /* Unmask the new notifier unless vector is masked. */
-    if (!msix_is_masked(dev, vector)) {
-        r = dev->msix_mask_notifier(dev, vector, false);
-        if (r < 0) {
-            return r;
-        }
     }
-    return r;
-}
-
-static int msix_unset_mask_notifier_for_vector(PCIDevice *dev, unsigned vector)
-{
-    int r = 0;
-    if (vector >= dev->msix_entries_nr || !dev->msix_entry_used[vector])
-        return 0;
-
     assert(dev->msix_mask_notifier);
-
-    /* Mask the old notifier unless it is already masked. */
-    if (!msix_is_masked(dev, vector)) {
-        r = dev->msix_mask_notifier(dev, vector, true);
-        if (r < 0) {
-            return r;
-        }
-    }
-    return r;
+    return dev->msix_mask_notifier(dev, vector, masked);
 }
 
 int msix_set_mask_notifier(PCIDevice *dev, msix_mask_notifier_func f)

@@ -625,7 +600,7 @@ int msix_set_mask_notifier(PCIDevice *dev, msix_mask_notifier_func f)
     assert(!dev->msix_mask_notifier);
     dev->msix_mask_notifier = f;
     for (n = 0; n < dev->msix_entries_nr; ++n) {
-        r = msix_set_mask_notifier_for_vector(dev, n);
+        r = msix_notify_if_unmasked(dev, n, false);
         if (r < 0) {
             goto undo;
         }

@@ -634,7 +609,7 @@ int msix_set_mask_notifier(PCIDevice *dev, msix_mask_notifier_func f)
 
 undo:
     while (--n >= 0) {
-        msix_unset_mask_notifier_for_vector(dev, n);
+        msix_notify_if_unmasked(dev, n, true);
     }
     dev->msix_mask_notifier = NULL;
     return r;

@@ -645,7 +620,7 @@ int msix_unset_mask_notifier(PCIDevice *dev)
     int r, n;
     assert(dev->msix_mask_notifier);
     for (n = 0; n < dev->msix_entries_nr; ++n) {
-        r = msix_unset_mask_notifier_for_vector(dev, n);
+        r = msix_notify_if_unmasked(dev, n, true);
         if (r < 0) {
             goto undo;
         }

@@ -655,7 +630,7 @@ int msix_unset_mask_notifier(PCIDevice *dev)
 
 undo:
     while (--n >= 0) {
-        msix_set_mask_notifier_for_vector(dev, n);
+        msix_notify_if_unmasked(dev, n, false);
     }
     return r;
 }
--

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Quoted 6 lines · Michael S. Tsirkin

Quoted 3 lines · Alex Williamson

You could always keep the functions as separate wrapper callers of the common function so you only need to keep true = unset, false = set straight in one place. Thanks,

Quoted 4 lines

Just to show why it does not work, I did exactly this: as you see the code is shorter but the true/false magic gets spread: it was in 2 places, (set/unset) now it is in 4 places and it is within the loop, in code that is more complex.

You seem to have missed the wrapper function. I'm simply suggesting something like this:

Quoted 7 lines · Alex Williamson

Quoted 6 lines · Michael S. Tsirkin

Quoted 3 lines · Alex Williamson

You could always keep the functions as separate wrapper callers of the common function so you only need to keep true = unset, false = set straight in one place. Thanks,

Quoted 7 lines

Quoted 4 lines

Just to show why it does not work, I did exactly this: as you see the code is shorter but the true/false magic gets spread: it was in 2 places, (set/unset) now it is in 4 places and it is within the loop, in code that is more complex.

You seem to have missed the wrapper function. I'm simply suggesting something like this:

Good idea. I tweaked the code a bit more and came up with this:
I think I will keep this as an incremental patch just to keep diffs small.

msix: factor out mask notifier code

Move some common code handling msix mask notifiers to a function.

Signed-off-by Michael S. Tsirkin <[email protected]>

hw/msix.c +5 -14

index 3d4dd61..5f66d20 100644
@@ -583,40 +583,26 @@ void msix_unuse_all_vectors(PCIDevice *dev)
     msix_free_irq_entries(dev);
 }
 
-static int msix_set_mask_notifier_for_vector(PCIDevice *dev, unsigned vector)
+/* Invoke the notifier if vector entry is used and unmasked. */
+static int msix_notify_if_unmasked(PCIDevice *dev, unsigned vector, int masked)
 {
-    int r = 0;
-    if (vector >= dev->msix_entries_nr || !dev->msix_entry_used[vector])
-        return 0;
-
     assert(dev->msix_mask_notifier);
-
-    /* Unmask the new notifier unless vector is masked. */
-    if (!msix_is_masked(dev, vector)) {
-        r = dev->msix_mask_notifier(dev, vector, false);
-        if (r < 0) {
-            return r;
-        }
+    if (!dev->msix_entry_used[vector] || msix_is_masked(dev, vector)) {
+        return 0;
     }
-    return r;
+    return dev->msix_mask_notifier(dev, vector, masked);
 }
 
-static int msix_unset_mask_notifier_for_vector(PCIDevice *dev, unsigned vector)

hw/msix.c +4 -8

-    /* Mask the old notifier unless it is already masked. */
-    if (!msix_is_masked(dev, vector)) {
-        r = dev->msix_mask_notifier(dev, vector, true);
-        if (r < 0) {
-            return r;
-        }
-    }
-    return r;
+static int msix_unset_mask_notifier_for_vector(PCIDevice *dev, unsigned vector)
+{
+	/* Notifier will be unset. Invoke it to mask unmasked entries. */
+	return msix_notify_if_unmasked(dev, vector, 1); 
 }
 
 int msix_set_mask_notifier(PCIDevice *dev, msix_mask_notifier_func f)

Looks fine except for the extra white space here and copied below. Thanks,

Alex