[PATCH v2 03/12] VT-d: parse ACPI "SoC Integrated Address Translation Cache Reporting Structure"s

[Jan Beulich <jbeulich@xxxxxxxx>]

This is a prereq to us, in particular, respecting the "ATC required"
flag.

Note that ACPI_SATC_ATC_REQUIRED has its #define put in dmar.h, as we
try to keep actbl*.h in sync what Linux (who in turn inherit from ACPI
CA) has.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Lovely: On the SPR system with the SATC I tried passing "ats" (the
"required" flag is clear there), just to then hit "IOMMU#4: QI dev wait
descriptor taking too long" while setting up Dom0. The 2nd message there
doesn't ever appear, so the request never completes. Not sure whether
that's us doing something wrong or the hardware acting up. In the former
case I'd generally expect an IOMMU fault to be raised, though. FTR same
on 4.18 with just "VT-d: correct ATS checking for root complex
integrated devices" backported there.

Should we check scope entries for appropriate types? (If so, then also
for e.g. ATSR.)
---
v2: Move error case freeing to acpi_parse_one_satc(). Introduce #define
    for the flag bit. Style.

--- a/xen/drivers/passthrough/vtd/dmar.c
+++ b/xen/drivers/passthrough/vtd/dmar.c
@@ -47,6 +47,7 @@ LIST_HEAD_READ_MOSTLY(acpi_drhd_units);
 LIST_HEAD_READ_MOSTLY(acpi_rmrr_units);
 static LIST_HEAD_READ_MOSTLY(acpi_atsr_units);
 static LIST_HEAD_READ_MOSTLY(acpi_rhsa_units);
+static LIST_HEAD_READ_MOSTLY(acpi_satc_units);
 
 static struct acpi_table_header *__read_mostly dmar_table;
 static int __read_mostly dmar_flags;
@@ -750,6 +751,93 @@ acpi_parse_one_rhsa(struct acpi_dmar_hea
     return ret;
 }
 
+static int __init register_one_satc(struct acpi_satc_unit *satcu)
+{
+    bool ignore = false;
+    unsigned int i = 0;
+    int ret = 0;
+
+    /* Skip checking if segment is not accessible yet. */
+    if ( !pci_known_segment(satcu->segment) )
+        i = UINT_MAX;
+
+    for ( ; i < satcu->scope.devices_cnt; i++ )
+    {
+        uint8_t b = PCI_BUS(satcu->scope.devices[i]);
+        uint8_t d = PCI_SLOT(satcu->scope.devices[i]);
+        uint8_t f = PCI_FUNC(satcu->scope.devices[i]);
+
+        if ( !pci_device_detect(satcu->segment, b, d, f) )
+        {
+            dprintk(XENLOG_WARNING VTDPREFIX,
+                    " Non-existent device (%pp) is reported in SATC scope!\n",
+                    &PCI_SBDF(satcu->segment, b, d, f));
+            ignore = true;
+        }
+        else
+        {
+            ignore = false;
+            break;
+        }
+    }
+
+    if ( ignore )
+    {
+        dprintk(XENLOG_WARNING VTDPREFIX,
+                " Ignore SATC for seg %04x as no device under its scope is PCI 
discoverable\n",
+                satcu->segment);
+        return 1;
+    }
+
+    if ( iommu_verbose )
+        printk(VTDPREFIX " ATC required: %d\n", satcu->atc_required);
+
+    list_add(&satcu->list, &acpi_satc_units);
+
+    return ret;
+}
+
+static int __init
+acpi_parse_one_satc(const struct acpi_dmar_header *header)
+{
+    const struct acpi_dmar_satc *satc =
+        container_of(header, const struct acpi_dmar_satc, header);
+    struct acpi_satc_unit *satcu;
+    const void *dev_scope_start, *dev_scope_end;
+    int ret = acpi_dmar_check_length(header, sizeof(*satc));
+
+    if ( ret )
+        return ret;
+
+    satcu = xzalloc(struct acpi_satc_unit);
+    if ( !satcu )
+        return -ENOMEM;
+
+    satcu->segment = satc->segment;
+    satcu->atc_required = satc->flags & ACPI_SATC_ATC_REQUIRED;
+
+    dev_scope_start = (const void *)(satc + 1);
+    dev_scope_end   = (const void *)satc + header->length;
+    ret = acpi_parse_dev_scope(dev_scope_start, dev_scope_end,
+                               &satcu->scope, SATC_TYPE, satc->segment);
+
+    if ( !ret && satcu->scope.devices_cnt )
+        ret = register_one_satc(satcu);
+
+    if ( ret )
+    {
+        scope_devices_free(&satcu->scope);
+        xfree(satcu);
+    }
+
+    /*
+     * register_one_satc() returns greater than 0 when a specified PCIe
+     * device cannot be detected. To prevent VT-d from being disabled in
+     * such cases, make the return value 0 here.
+     */
+    return ret > 0 ? 0 : ret;
+}
+
 static int __init cf_check acpi_parse_dmar(struct acpi_table_header *table)
 {
     struct acpi_table_dmar *dmar;
@@ -803,6 +891,13 @@ static int __init cf_check acpi_parse_dm
                 printk(VTDPREFIX "found ACPI_DMAR_RHSA:\n");
             ret = acpi_parse_one_rhsa(entry_header);
             break;
+
+        case ACPI_DMAR_TYPE_SATC:
+            if ( iommu_verbose )
+                printk(VTDPREFIX "found ACPI_DMAR_SATC:\n");
+            ret = acpi_parse_one_satc(entry_header);
+            break;
+
         default:
             dprintk(XENLOG_WARNING VTDPREFIX,
                     "Ignore unknown DMAR structure type (%#x)\n",
--- a/xen/drivers/passthrough/vtd/dmar.h
+++ b/xen/drivers/passthrough/vtd/dmar.h
@@ -91,6 +91,16 @@ struct acpi_rhsa_unit {
     u32    proximity_domain;
 };
 
+struct acpi_satc_unit {
+    struct dmar_scope scope;
+    struct list_head list;
+    uint16_t segment;
+    bool atc_required:1;
+};
+
+/* In lieu of a definition in actbl2.h. */
+#define ACPI_SATC_ATC_REQUIRED (1U << 0)
+
 #define for_each_drhd_unit(drhd) \
     list_for_each_entry(drhd, &acpi_drhd_units, list)
 
@@ -106,6 +116,7 @@ struct acpi_atsr_unit *acpi_find_matched
 #define DMAR_TYPE 1
 #define RMRR_TYPE 2
 #define ATSR_TYPE 3
+#define SATC_TYPE 4
 
 #define DMAR_OPERATION_TIMEOUT MILLISECS(1000)
 
--- a/xen/include/acpi/actbl2.h
+++ b/xen/include/acpi/actbl2.h
@@ -345,7 +345,8 @@ enum acpi_dmar_type {
        ACPI_DMAR_TYPE_RESERVED_MEMORY = 1,
        ACPI_DMAR_TYPE_ATSR = 2,
        ACPI_DMAR_HARDWARE_AFFINITY = 3,
-       ACPI_DMAR_TYPE_RESERVED = 4     /* 4 and greater are reserved */
+       ACPI_DMAR_TYPE_SATC = 5,
+       ACPI_DMAR_TYPE_RESERVED = 7     /* 7 and greater are reserved */
 };
 
 /* DMAR Device Scope structure */
@@ -427,6 +428,15 @@ struct acpi_dmar_rhsa {
        u32 proximity_domain;
 };
 
+/* 5: SOC Integrated Address Translation Cache Reporting Structure */
+
+struct acpi_dmar_satc {
+       struct acpi_dmar_header header;
+       uint8_t flags;
+       uint8_t reserved;
+       uint16_t segment;
+};
+
 
/*******************************************************************************
  *
  * HPET - High Precision Event Timer table