[xen staging] x86/IOMMU: mark IOMMU / intremap not in use when ACPI tables are missing

[patchbot@xxxxxxx]

commit 46c4061cd2bf69e8039021af615c2bdb94e50088
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Thu Nov 4 14:44:01 2021 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Nov 4 14:44:01 2021 +0100

    x86/IOMMU: mark IOMMU / intremap not in use when ACPI tables are missing
    
    x2apic_bsp_setup() gets called ahead of iommu_setup(), and since x2APIC
    mode (physical vs clustered) depends on iommu_intremap, that variable
    needs to be set to off as soon as we know we can't / won't enable
    interrupt remapping, i.e. in particular when parsing of the respective
    ACPI tables failed. Move the turning off of iommu_intremap from AMD
    specific code into acpi_iommu_init(), accompanying it by clearing of
    iommu_enable.
    
    Take the opportunity and also fully skip ACPI table parsing logic on
    VT-d when both "iommu=off" and "iommu=no-intremap" are in effect anyway,
    like was already the case for AMD.
    
    The tag below only references the commit uncovering a pre-existing
    anomaly.
    
    Fixes: d8bd82327b0f ("AMD/IOMMU: obtain IVHD type to use earlier")
    Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
    Release-Acked-by: Ian Jackson <iwj@xxxxxxxxxxxxxx>
---
 xen/drivers/passthrough/amd/pci_amd_iommu.c |  6 ------
 xen/drivers/passthrough/vtd/dmar.c          |  6 +-----
 xen/drivers/passthrough/x86/iommu.c         | 18 ++++++++++++++++++
 xen/include/asm-x86/acpi.h                  |  8 +-------
 4 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/xen/drivers/passthrough/amd/pci_amd_iommu.c 
b/xen/drivers/passthrough/amd/pci_amd_iommu.c
index 03228a9952..9642bba43a 100644
--- a/xen/drivers/passthrough/amd/pci_amd_iommu.c
+++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c
@@ -183,9 +183,6 @@ int __init acpi_ivrs_init(void)
 {
     int rc;
 
-    if ( !iommu_enable && !iommu_intremap )
-        return 0;
-
     rc = amd_iommu_get_supported_ivhd_type();
     if ( rc < 0 )
         return rc;
@@ -193,10 +190,7 @@ int __init acpi_ivrs_init(void)
     ivhd_type = rc;
 
     if ( (amd_iommu_detect_acpi() !=0) || (iommu_found() == 0) )
-    {
-        iommu_intremap = iommu_intremap_off;
         return -ENODEV;
-    }
 
     iommu_init_ops = &_iommu_init_ops;
 
diff --git a/xen/drivers/passthrough/vtd/dmar.c 
b/xen/drivers/passthrough/vtd/dmar.c
index d5ee367599..33a12b2ae9 100644
--- a/xen/drivers/passthrough/vtd/dmar.c
+++ b/xen/drivers/passthrough/vtd/dmar.c
@@ -777,11 +777,7 @@ static int __init acpi_parse_dmar(struct acpi_table_header 
*table)
     dmar = (struct acpi_table_dmar *)table;
     dmar_flags = dmar->flags;
 
-    if ( !iommu_enable && !iommu_intremap )
-    {
-        ret = -EINVAL;
-        goto out;
-    }
+    ASSERT(iommu_enable || iommu_intremap);
 
     if ( !dmar->width )
     {
diff --git a/xen/drivers/passthrough/x86/iommu.c 
b/xen/drivers/passthrough/x86/iommu.c
index 01dbd9b098..b2284ae001 100644
--- a/xen/drivers/passthrough/x86/iommu.c
+++ b/xen/drivers/passthrough/x86/iommu.c
@@ -41,6 +41,24 @@ enum iommu_intremap __read_mostly iommu_intremap = 
iommu_intremap_full;
 bool __read_mostly iommu_intpost;
 #endif
 
+void __init acpi_iommu_init(void)
+{
+    int ret;
+
+    if ( !iommu_enable && !iommu_intremap )
+        return;
+
+    ret = acpi_dmar_init();
+    if ( ret == -ENODEV )
+        ret = acpi_ivrs_init();
+
+    if ( ret )
+    {
+        iommu_enable = false;
+        iommu_intremap = iommu_intremap_off;
+    }
+}
+
 int __init iommu_hardware_setup(void)
 {
     struct IO_APIC_route_entry **ioapic_entries = NULL;
diff --git a/xen/include/asm-x86/acpi.h b/xen/include/asm-x86/acpi.h
index 7032f3a001..9a9cc4c240 100644
--- a/xen/include/asm-x86/acpi.h
+++ b/xen/include/asm-x86/acpi.h
@@ -141,16 +141,10 @@ extern u32 x86_acpiid_to_apicid[];
 extern u32 pmtmr_ioport;
 extern unsigned int pmtmr_width;
 
+void acpi_iommu_init(void);
 int acpi_dmar_init(void);
 int acpi_ivrs_init(void);
 
-static inline int acpi_iommu_init(void)
-{
-    int ret = acpi_dmar_init();
-
-    return ret == -ENODEV ? acpi_ivrs_init() : ret;
-}
-
 void acpi_mmcfg_init(void);
 
 /* Incremented whenever we transition through S3. Value is 1 during boot. */
--
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