[Xen-changelog] [xen-4.2-testing] IOMMU/ATS: fix maximum queue depth calculation

[Xen patchbot-4.2-testing <patchbot@xxxxxxx>]

# HG changeset patch
# User Jan Beulich <jbeulich@xxxxxxxx>
# Date 1355917993 -3600
# Node ID b533c473029ff99f0f130da758134acaec4f97d4
# Parent  df2a3515788de458742ed205b073fc5a2c7a9cef
IOMMU/ATS: fix maximum queue depth calculation

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@xxxxxxxx>
Acked-by Xiantao Zhang <xiantao.zhang@xxxxxxxxx>
Acked-by: Wei Huang <wei.huang2@xxxxxxx>
xen-unstable changeset: 26235:670b07e8d738
xen-unstable date: Wed Dec  5 08:52:14 UTC 2012
---


diff -r df2a3515788d -r b533c473029f xen/drivers/passthrough/amd/iommu_cmd.c
--- a/xen/drivers/passthrough/amd/iommu_cmd.c   Wed Dec 19 12:51:46 2012 +0100
+++ b/xen/drivers/passthrough/amd/iommu_cmd.c   Wed Dec 19 12:53:13 2012 +0100
@@ -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);
diff -r df2a3515788d -r b533c473029f xen/drivers/passthrough/ats.h
--- a/xen/drivers/passthrough/ats.h     Wed Dec 19 12:51:46 2012 +0100
+++ b/xen/drivers/passthrough/ats.h     Wed Dec 19 12:53:13 2012 +0100
@@ -30,7 +30,7 @@ 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;
diff -r df2a3515788d -r b533c473029f xen/drivers/passthrough/x86/ats.c
--- a/xen/drivers/passthrough/x86/ats.c Wed Dec 19 12:51:46 2012 +0100
+++ b/xen/drivers/passthrough/x86/ats.c Wed Dec 19 12:53:13 2012 +0100
@@ -93,7 +93,8 @@ int enable_ats_device(int seg, int bus, 
         pdev->devfn = devfn;
         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;
+        pdev->ats_queue_depth = value & ATS_QUEUE_DEPTH_MASK ?:
+                                ATS_QUEUE_DEPTH_MASK + 1;
         list_add(&pdev->list, &ats_devices);
     }
 

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