The capabilities register field is a 5-bit value, and the 5 bits all
being zero actually means 32 entries.
Under the assumption that amd_iommu_flush_iotlb() really just tried
to correct for the miscalculation above when adding 32 to the value,
that adjustment is also being removed.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- a/xen/drivers/passthrough/amd/iommu_cmd.c
+++ b/xen/drivers/passthrough/amd/iommu_cmd.c
@@ -321,7 +321,7 @@ void amd_iommu_flush_iotlb(struct pci_de
req_id = get_dma_requestor_id(iommu->seg, bdf);
queueid = req_id;
- maxpend = (ats_pdev->ats_queue_depth + 32) & 0xff;
+ maxpend = ats_pdev->ats_queue_depth & 0xff;
/* send INVALIDATE_IOTLB_PAGES command */
spin_lock_irqsave(&iommu->lock, flags);
--- a/xen/drivers/passthrough/ats.h
+++ b/xen/drivers/passthrough/ats.h
@@ -28,7 +28,7 @@ struct pci_ats_dev {
#define ATS_REG_CAP 4
#define ATS_REG_CTL 6
-#define ATS_QUEUE_DEPTH_MASK 0xF
+#define ATS_QUEUE_DEPTH_MASK 0x1f
#define ATS_ENABLE (1<<15)
extern struct list_head ats_devices;
--- a/xen/drivers/passthrough/x86/ats.c
+++ b/xen/drivers/passthrough/x86/ats.c
@@ -94,6 +94,8 @@ int enable_ats_device(int seg, int bus,
value = pci_conf_read16(seg, bus, PCI_SLOT(devfn),
PCI_FUNC(devfn), pos + ATS_REG_CAP);
pdev->ats_queue_depth = value & ATS_QUEUE_DEPTH_MASK;
+ if ( !pdev->ats_queue_depth )
+ pdev->ats_queue_depth = ATS_QUEUE_DEPTH_MASK + 1;
list_add(&pdev->list, &ats_devices);
}
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