[Xen-devel] [PATCH v3 1/4] iommu: introduce dom0-iommu option

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

To select the iommu configuration used by Dom0. This option supersedes
iommu=dom0-strict|dom0-passthrough.

No functional change.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
Changes since v2:
 - Change the style and text used in the xen command line document.
 - Don't allow none, strict or relaxed to use the no- prefix.

Changes since v1:
 - New in this version.
---
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Julien Grall <julien.grall@xxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Tim Deegan <tim@xxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
Cc: Brian Woods <brian.woods@xxxxxxx>
Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 docs/misc/xen-command-line.markdown         | 23 +++++++++++
 xen/arch/x86/x86_64/mm.c                    |  3 +-
 xen/drivers/passthrough/amd/iommu_init.c    |  2 +-
 xen/drivers/passthrough/amd/pci_amd_iommu.c |  4 +-
 xen/drivers/passthrough/iommu.c             | 42 +++++++++++++++++----
 xen/drivers/passthrough/vtd/iommu.c         | 16 ++++----
 xen/include/xen/iommu.h                     |  6 ++-
 7 files changed, 75 insertions(+), 21 deletions(-)

diff --git a/docs/misc/xen-command-line.markdown 
b/docs/misc/xen-command-line.markdown
index 65b4754418..ea451f088e 100644
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -1150,12 +1150,18 @@ detection of systems known to misbehave upon accesses 
to that port.
 
 > `dom0-passthrough`
 
+> **WARNING: This command line option is deprecated, and superseded by
+> _dom0-iommu=none_ - using both options in combination is undefined.**
+
 > Default: `false`
 
 >> Control whether to disable DMA remapping for Dom0.
 
 > `dom0-strict`
 
+> **WARNING: This command line option is deprecated, and superseded by
+> _dom0-iommu=strict_ - using both options in combination is undefined.**
+
 > Default: `false`
 
 >> Control whether to set up DMA remapping only for the memory Dom0 actually
@@ -1198,6 +1204,23 @@ detection of systems known to misbehave upon accesses to 
that port.
 
 >> Enable IOMMU debugging code (implies `verbose`).
 
+### dom0-iommu
+> `= List of [ none | strict | relaxed ]`
+
+* `none`: disables DMA remapping for Dom0.
+
+The following two options control how RAM regions are mapped in the iommu for
+PV Dom0:
+
+* `strict`: sets up DMA remapping only for the memory Dom0 actually got
+  assigned.
+
+* `relaxed`: sets DMA remapping for all the host RAM except regions in use by
+  Xen. This is the default iommu behaviour.
+
+Note that all the above options are mutually exclusive. Specifying more than
+one on the `dom0-iommu` command line will result in undefined behavior.
+
 ### iommu\_dev\_iotlb\_timeout
 > `= <integer>`
 
diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index cca4ae926e..84226b3326 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -1426,7 +1426,8 @@ int memory_add(unsigned long spfn, unsigned long epfn, 
unsigned int pxm)
     if ( ret )
         goto destroy_m2p;
 
-    if ( iommu_enabled && !iommu_passthrough && !need_iommu(hardware_domain) )
+    if ( iommu_enabled && !iommu_dom0_passthrough &&
+         !need_iommu(hardware_domain) )
     {
         for ( i = spfn; i < epfn; i++ )
             if ( iommu_map_page(hardware_domain, i, i, 
IOMMUF_readable|IOMMUF_writable) )
diff --git a/xen/drivers/passthrough/amd/iommu_init.c 
b/xen/drivers/passthrough/amd/iommu_init.c
index 474992a75a..ad8c48be1c 100644
--- a/xen/drivers/passthrough/amd/iommu_init.c
+++ b/xen/drivers/passthrough/amd/iommu_init.c
@@ -1062,7 +1062,7 @@ static void __init amd_iommu_init_cleanup(void)
     radix_tree_destroy(&ivrs_maps, xfree);
 
     iommu_enabled = 0;
-    iommu_passthrough = 0;
+    iommu_dom0_passthrough = false;
     iommu_intremap = 0;
     iommuv2_enabled = 0;
 }
diff --git a/xen/drivers/passthrough/amd/pci_amd_iommu.c 
b/xen/drivers/passthrough/amd/pci_amd_iommu.c
index 12d2695b89..eeacf713e4 100644
--- a/xen/drivers/passthrough/amd/pci_amd_iommu.c
+++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c
@@ -121,7 +121,7 @@ static void amd_iommu_setup_domain_device(
     BUG_ON( !hd->arch.root_table || !hd->arch.paging_mode ||
             !iommu->dev_table.buffer );
 
-    if ( iommu_passthrough && is_hardware_domain(domain) )
+    if ( iommu_dom0_passthrough && is_hardware_domain(domain) )
         valid = 0;
 
     if ( ats_enabled )
@@ -256,7 +256,7 @@ static void __hwdom_init amd_iommu_hwdom_init(struct domain 
*d)
     if ( allocate_domain_resources(dom_iommu(d)) )
         BUG();
 
-    if ( !iommu_passthrough && !need_iommu(d) )
+    if ( !iommu_dom0_passthrough && !need_iommu(d) )
     {
         int rc = 0;
 
diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index 70d218f910..830560bdcf 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -22,6 +22,7 @@
 #include <xsm/xsm.h>
 
 static int parse_iommu_param(const char *s);
+static int parse_dom0_iommu_param(const char *s);
 static void iommu_dump_p2m_table(unsigned char key);
 
 unsigned int __read_mostly iommu_dev_iotlb_timeout = 1000;
@@ -52,11 +53,9 @@ custom_param("iommu", parse_iommu_param);
 bool_t __initdata iommu_enable = 1;
 bool_t __read_mostly iommu_enabled;
 bool_t __read_mostly force_iommu;
-bool_t __hwdom_initdata iommu_dom0_strict;
 bool_t __read_mostly iommu_verbose;
 bool_t __read_mostly iommu_workaround_bios_bug;
 bool_t __read_mostly iommu_igfx = 1;
-bool_t __read_mostly iommu_passthrough;
 bool_t __read_mostly iommu_snoop = 1;
 bool_t __read_mostly iommu_qinval = 1;
 bool_t __read_mostly iommu_intremap = 1;
@@ -72,6 +71,10 @@ bool_t __read_mostly iommu_hap_pt_share = 1;
 bool_t __read_mostly iommu_debug;
 bool_t __read_mostly amd_iommu_perdev_intremap = 1;
 
+custom_param("dom0-iommu", parse_dom0_iommu_param);
+bool __hwdom_initdata iommu_dom0_strict;
+bool __read_mostly iommu_dom0_passthrough;
+
 DEFINE_PER_CPU(bool_t, iommu_dont_flush_iotlb);
 
 DEFINE_SPINLOCK(iommu_pt_cleanup_lock);
@@ -121,7 +124,7 @@ static int __init parse_iommu_param(const char *s)
         else if ( !strncmp(s, "amd-iommu-perdev-intremap", ss - s) )
             amd_iommu_perdev_intremap = val;
         else if ( !strncmp(s, "dom0-passthrough", ss - s) )
-            iommu_passthrough = val;
+            iommu_dom0_passthrough = val;
         else if ( !strncmp(s, "dom0-strict", ss - s) )
             iommu_dom0_strict = val;
         else if ( !strncmp(s, "sharept", ss - s) )
@@ -135,6 +138,31 @@ static int __init parse_iommu_param(const char *s)
     return rc;
 }
 
+static int __init parse_dom0_iommu_param(const char *s)
+{
+    const char *ss;
+    int rc = 0;
+
+    do {
+        ss = strchr(s, ',');
+        if ( !ss )
+            ss = strchr(s, '\0');
+
+        if ( !strncmp(s, "none", ss - s) )
+            iommu_dom0_passthrough = true;
+        else if ( !strncmp(s, "strict", ss - s) )
+            iommu_dom0_strict = true;
+        else if ( !strncmp(s, "relaxed", ss - s) )
+            iommu_dom0_strict = false;
+        else
+            rc = -EINVAL;
+
+        s = ss + 1;
+    } while ( *ss );
+
+    return rc;
+}
+
 int iommu_domain_init(struct domain *d)
 {
     struct domain_iommu *hd = dom_iommu(d);
@@ -158,7 +186,7 @@ static void __hwdom_init check_hwdom_reqs(struct domain *d)
 
     arch_iommu_check_autotranslated_hwdom(d);
 
-    if ( iommu_passthrough )
+    if ( iommu_dom0_passthrough )
         panic("Dom0 uses paging translated mode, dom0-passthrough must not be "
               "enabled\n");
 
@@ -372,7 +400,7 @@ int __init iommu_setup(void)
     bool_t force_intremap = force_iommu && iommu_intremap;
 
     if ( iommu_dom0_strict )
-        iommu_passthrough = 0;
+        iommu_dom0_passthrough = false;
 
     if ( iommu_enable )
     {
@@ -393,14 +421,14 @@ int __init iommu_setup(void)
     if ( !iommu_enabled )
     {
         iommu_snoop = 0;
-        iommu_passthrough = 0;
+        iommu_dom0_passthrough = false;
         iommu_dom0_strict = 0;
     }
     printk("I/O virtualisation %sabled\n", iommu_enabled ? "en" : "dis");
     if ( iommu_enabled )
     {
         printk(" - Dom0 mode: %s\n",
-               iommu_passthrough ? "Passthrough" :
+               iommu_dom0_passthrough ? "Passthrough" :
                iommu_dom0_strict ? "Strict" : "Relaxed");
         printk("Interrupt remapping %sabled\n", iommu_intremap ? "en" : "dis");
         tasklet_init(&iommu_pt_cleanup_tasklet, iommu_free_pagetables, 0);
diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index 1710256823..8ac774215b 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -1304,7 +1304,7 @@ static void __hwdom_init intel_iommu_hwdom_init(struct 
domain *d)
 {
     struct acpi_drhd_unit *drhd;
 
-    if ( !iommu_passthrough && is_pv_domain(d) )
+    if ( !iommu_dom0_passthrough && is_pv_domain(d) )
     {
         /* Set up 1:1 page table for hardware domain. */
         vtd_set_hwdom_mapping(d);
@@ -1391,7 +1391,7 @@ int domain_context_mapping_one(
         return res;
     }
 
-    if ( iommu_passthrough && is_hardware_domain(domain) )
+    if ( iommu_dom0_passthrough && is_hardware_domain(domain) )
     {
         context_set_translation_type(*context, CONTEXT_TT_PASS_THRU);
         agaw = level_to_agaw(iommu->nr_pt_levels);
@@ -1781,7 +1781,7 @@ static int __must_check intel_iommu_map_page(struct 
domain *d,
         return 0;
 
     /* Do nothing if hardware domain and iommu supports pass thru. */
-    if ( iommu_passthrough && is_hardware_domain(d) )
+    if ( iommu_dom0_passthrough && is_hardware_domain(d) )
         return 0;
 
     spin_lock(&hd->arch.mapping_lock);
@@ -1826,7 +1826,7 @@ static int __must_check intel_iommu_unmap_page(struct 
domain *d,
                                                unsigned long gfn)
 {
     /* Do nothing if hardware domain and iommu supports pass thru. */
-    if ( iommu_passthrough && is_hardware_domain(d) )
+    if ( iommu_dom0_passthrough && is_hardware_domain(d) )
         return 0;
 
     return dma_pte_clear_one(d, (paddr_t)gfn << PAGE_SHIFT_4K);
@@ -2269,8 +2269,8 @@ int __init intel_vtd_setup(void)
         if ( iommu_snoop && !ecap_snp_ctl(iommu->ecap) )
             iommu_snoop = 0;
 
-        if ( iommu_passthrough && !ecap_pass_thru(iommu->ecap) )
-            iommu_passthrough = 0;
+        if ( iommu_dom0_passthrough && !ecap_pass_thru(iommu->ecap) )
+            iommu_dom0_passthrough = false;
 
         if ( iommu_qinval && !ecap_queued_inval(iommu->ecap) )
             iommu_qinval = 0;
@@ -2308,7 +2308,7 @@ int __init intel_vtd_setup(void)
 
 #define P(p,s) printk("Intel VT-d %s %senabled.\n", s, (p)? "" : "not ")
     P(iommu_snoop, "Snoop Control");
-    P(iommu_passthrough, "Dom0 DMA Passthrough");
+    P(iommu_dom0_passthrough, "Dom0 DMA Passthrough");
     P(iommu_qinval, "Queued Invalidation");
     P(iommu_intremap, "Interrupt Remapping");
     P(iommu_intpost, "Posted Interrupt");
@@ -2330,7 +2330,7 @@ int __init intel_vtd_setup(void)
  error:
     iommu_enabled = 0;
     iommu_snoop = 0;
-    iommu_passthrough = 0;
+    iommu_dom0_passthrough = false;
     iommu_qinval = 0;
     iommu_intremap = 0;
     iommu_intpost = 0;
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index 6b42e3b876..c0c6975ac4 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -29,13 +29,15 @@
 #include <asm/iommu.h>
 
 extern bool_t iommu_enable, iommu_enabled;
-extern bool_t force_iommu, iommu_dom0_strict, iommu_verbose;
-extern bool_t iommu_workaround_bios_bug, iommu_igfx, iommu_passthrough;
+extern bool_t force_iommu, iommu_verbose;
+extern bool_t iommu_workaround_bios_bug, iommu_igfx;
 extern bool_t iommu_snoop, iommu_qinval, iommu_intremap, iommu_intpost;
 extern bool_t iommu_hap_pt_share;
 extern bool_t iommu_debug;
 extern bool_t amd_iommu_perdev_intremap;
 
+extern bool iommu_dom0_strict, iommu_dom0_passthrough;
+
 extern unsigned int iommu_dev_iotlb_timeout;
 
 int iommu_setup(void);
-- 
2.18.0


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