[Xen-devel] [PATCH] amd iommu: Add workaround for erratum 732 & 733

[Wei Wang <wei.wang2@xxxxxxx>]

Hi Jan
This patch implements the suggested workaround for erratum 732 & 733. It 
is mostly derived from the Linux patch recently posted. Please review it.
Thanks,
Wei

# HG changeset patch
# User Wei Wang <wei.wang2@xxxxxxx>
# Date 1337690747 -7200
# Node ID 06aebc361de7f308b262b008153ae4549c4480c2
# Parent  592d15bd4d5ec58486d32ee9998319e7c95fcd66
amd iommu: Add workaround for erratum 733 & 733

Signed-off-by: Wei Wang <wei.wang2@xxxxxxx>

diff -r 592d15bd4d5e -r 06aebc361de7 
xen/drivers/passthrough/amd/iommu_init.c
--- a/xen/drivers/passthrough/amd/iommu_init.c    Fri May 18 16:19:21 
2012 +0100
+++ b/xen/drivers/passthrough/amd/iommu_init.c    Tue May 22 14:45:47 
2012 +0200
@@ -29,6 +29,7 @@
 #include <asm/hvm/svm/amd-iommu-proto.h>
 #include <asm-x86/fixmap.h>
 #include <mach_apic.h>
+#include <xen/delay.h>

 static int __initdata nr_amd_iommus;

@@ -566,6 +567,7 @@ static void parse_event_log_entry(struct
     u16 domain_id, device_id, bdf, cword;
     u32 code;
     u64 *addr;
+    int count = 0;
     char * event_str[] = {"ILLEGAL_DEV_TABLE_ENTRY",
                           "IO_PAGE_FAULT",
                           "DEV_TABLE_HW_ERROR",
@@ -575,9 +577,27 @@ static void parse_event_log_entry(struct
                           "IOTLB_INV_TIMEOUT",
                           "INVALID_DEV_REQUEST"};

+retry:
     code = get_field_from_reg_u32(entry[1], IOMMU_EVENT_CODE_MASK,
                                             IOMMU_EVENT_CODE_SHIFT);

+    /* Workaround for erratum 732.
+     * it can happen that the tail pointer is updated before the actual 
entry
+     * is written. Suggested by RevGuide, we initialize the event log 
buffer to
+     * all zeros and write event log entries to zero after they are 
processed.
+     */
+
+    if ( code == 0 )
+    {
+        if ( unlikely(++count == IOMMU_LOG_ENTRY_TIMEOUT) )
+        {
+            AMD_IOMMU_DEBUG("AMD-Vi: No event written to event log\n");
+            return;
+        }
+        udelay(1);
+        goto retry;
+    }
+
     if ( (code > IOMMU_EVENT_INVALID_DEV_REQUEST) ||
         (code < IOMMU_EVENT_ILLEGAL_DEV_TABLE_ENTRY) )
     {
@@ -615,6 +635,8 @@ static void parse_event_log_entry(struct
         AMD_IOMMU_DEBUG("event 0x%08x 0x%08x 0x%08x 0x%08x\n", entry[0],
                         entry[1], entry[2], entry[3]);
     }
+
+    memset(entry, 0, IOMMU_EVENT_LOG_ENTRY_SIZE);
 }

 static void iommu_check_event_log(struct amd_iommu *iommu)
@@ -646,10 +668,32 @@ void parse_ppr_log_entry(struct amd_iomm
 {

     u16 device_id;
-    u8 bus, devfn;
+    u8 bus, devfn, code;
     struct pci_dev *pdev;
     struct domain *d;
+    int count = 0;

+retry:
+    code = get_field_from_reg_u32(entry[1], IOMMU_PPR_LOG_CODE_MASK,
+                                            IOMMU_PPR_LOG_CODE_SHIFT);
+
+    /* Workaround for erratum 733.
+     * it can happen that the tail pointer is updated before the actual 
entry
+     * is written. Suggested by RevGuide, we initialize the ppr log 
buffer to
+     * all zeros and write ppr log entries to zero after they are 
processed.
+     */
+
+    if ( code == 0 )
+    {
+        if ( unlikely(++count == IOMMU_LOG_ENTRY_TIMEOUT) )
+        {
+            AMD_IOMMU_DEBUG("AMD-Vi: No ppr written to ppr log\n");
+            return;
+        }
+        udelay(1);
+        goto retry;
+    }
+
     /* here device_id is physical value */
     device_id = iommu_get_devid_from_cmd(entry[0]);
     bus = PCI_BUS(device_id);
@@ -665,6 +709,8 @@ void parse_ppr_log_entry(struct amd_iomm
     d = pdev->domain;

     guest_iommu_add_ppr_log(d, entry);
+
+    memset(entry, 0, IOMMU_PPR_LOG_ENTRY_SIZE);
 }

 static void iommu_check_ppr_log(struct amd_iommu *iommu)
diff -r 592d15bd4d5e -r 06aebc361de7 
xen/include/asm-x86/hvm/svm/amd-iommu-defs.h
--- a/xen/include/asm-x86/hvm/svm/amd-iommu-defs.h    Fri May 18 
16:19:21 2012 +0100
+++ b/xen/include/asm-x86/hvm/svm/amd-iommu-defs.h    Tue May 22 
14:45:47 2012 +0200
@@ -301,6 +301,10 @@
 #define IOMMU_PPR_LOG_TAIL_OFFSET                       0x2038
 #define IOMMU_PPR_LOG_DEVICE_ID_MASK                    0x0000FFFF
 #define IOMMU_PPR_LOG_DEVICE_ID_SHIFT                   0
+#define IOMMU_PPR_LOG_CODE_MASK                         0xF0000000
+#define IOMMU_PPR_LOG_CODE_SHIFT                        28
+
+#define IOMMU_LOG_ENTRY_TIMEOUT                         100000

 /* Control Register */
 #define IOMMU_CONTROL_MMIO_OFFSET            0x18


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