[PATCH v2 5/9] IOMMU: add common API for device reserved memory

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

Add API similar to rmrr= and ivmd= arguments, but in a common code. This
will allow drivers to register reserved memory regardless of the IOMMU
vendor.
The direct reason for this API is xhci-dbc console driver (aka xue),
that needs to use DMA. But future change may unify command line
arguments for user-supplied reserved memory, and it may be useful for
other drivers in the future too.

This commit just introduces an API, subsequent patches will plug it in
appropriate places. The reserved memory ranges needs to be saved
locally, because at the point when they are collected, Xen doesn't know
yet which IOMMU driver will be used.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
---
 xen/drivers/passthrough/iommu.c | 40 ++++++++++++++++++++++++++++++++++-
 xen/include/xen/iommu.h         | 11 +++++++++-
 2 files changed, 51 insertions(+)

diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index 75df3aa8ddaa..257691ad19ef 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -651,6 +651,46 @@ bool_t iommu_has_feature(struct domain *d, enum 
iommu_feature feature)
     return is_iommu_enabled(d) && test_bit(feature, dom_iommu(d)->features);
 }
 
+#define MAX_EXTRA_RESERVED_RANGES 20
+struct extra_reserved_range {
+    xen_pfn_t start;
+    xen_ulong_t nr;
+    u32 sbdf;
+};
+static unsigned int __initdata nr_extra_reserved_ranges;
+static struct extra_reserved_range __initdata 
extra_reserved_ranges[MAX_EXTRA_RESERVED_RANGES];
+
+int iommu_add_extra_reserved_device_memory(xen_pfn_t start, xen_ulong_t nr, 
u32 sbdf)
+{
+    unsigned int idx;
+
+    if ( nr_extra_reserved_ranges >= MAX_EXTRA_RESERVED_RANGES )
+        return -ENOMEM;
+
+    idx = nr_extra_reserved_ranges++;
+    extra_reserved_ranges[idx].start = start;
+    extra_reserved_ranges[idx].nr = nr;
+    extra_reserved_ranges[idx].sbdf = sbdf;
+    return 0;
+}
+
+int iommu_get_extra_reserved_device_memory(iommu_grdm_t *func, void *ctxt)
+{
+    unsigned int idx;
+    int ret;
+
+    for ( idx = 0; idx < nr_extra_reserved_ranges; idx++ )
+    {
+        ret = func(extra_reserved_ranges[idx].start,
+                   extra_reserved_ranges[idx].nr,
+                   extra_reserved_ranges[idx].sbdf,
+                   ctxt);
+        if ( ret < 0 )
+            return ret;
+    }
+    return 0;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index 79529adf1fa5..7640f40d77b5 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -297,6 +297,17 @@ struct iommu_ops {
 #endif
 };
 
+/*
+ * To be called by Xen internally, to register extra RMRR/IVMD ranges.
+ * Needs to be called before IOMMU initialization.
+ */
+extern int iommu_add_extra_reserved_device_memory(xen_pfn_t start, xen_ulong_t 
nr, u32 sbdf);
+/*
+ * To be called by specific IOMMU driver during initialization,
+ * to fetch ranges registered with iommu_add_extra_reserved_device_memory().
+ */
+extern int iommu_get_extra_reserved_device_memory(iommu_grdm_t *func, void 
*ctxt);
+
 #include <asm/iommu.h>
 
 #ifndef iommu_call
-- 
git-series 0.9.1