[Xen-devel] [RFC PATCH v2 04/26] ARM: GICv3 ITS: map ITS command buffer

[Andre Przywara <andre.przywara@xxxxxxx>]

Instead of directly manipulating the tables in memory, an ITS driver
sends commands via a ring buffer to the ITS h/w to create or alter the
LPI mappings.
Allocate memory for that buffer and tell the ITS about it to be able
to send ITS commands.

Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
---
 xen/arch/arm/gic-its.c        | 27 +++++++++++++++++++++++++++
 xen/include/asm-arm/gic-its.h |  3 +++
 2 files changed, 30 insertions(+)

diff --git a/xen/arch/arm/gic-its.c b/xen/arch/arm/gic-its.c
index f1540b2..2fb3bcb 100644
--- a/xen/arch/arm/gic-its.c
+++ b/xen/arch/arm/gic-its.c
@@ -18,6 +18,7 @@
 
 #include <xen/config.h>
 #include <xen/lib.h>
+#include <xen/err.h>
 #include <xen/device_tree.h>
 #include <xen/libfdt/libfdt.h>
 #include <xen/sizes.h>
@@ -38,6 +39,8 @@ static DEFINE_PER_CPU(void *, pending_table);
 
 #define MAX_PHYS_LPIS   (BIT_ULL(lpi_data.host_lpi_bits) - 8192)
 
+#define ITS_CMD_QUEUE_SZ                                SZ_64K
+
 #define BASER_ATTR_MASK                                           \
         ((0x3UL << GITS_BASER_SHAREABILITY_SHIFT)               | \
          (0x7UL << GITS_BASER_OUTER_CACHEABILITY_SHIFT)         | \
@@ -55,6 +58,26 @@ static uint64_t encode_phys_addr(paddr_t addr, int page_bits)
     return ret | (addr & GENMASK(51, 48)) >> (48 - 12);
 }
 
+static void *its_map_cbaser(void __iomem *cbasereg)
+{
+    uint64_t attr, reg;
+    void *buffer;
+
+    attr  = GIC_BASER_InnerShareable << GITS_BASER_SHAREABILITY_SHIFT;
+    attr |= GIC_BASER_CACHE_SameAsInner << GITS_BASER_OUTER_CACHEABILITY_SHIFT;
+    attr |= GIC_BASER_CACHE_RaWaWb << GITS_BASER_INNER_CACHEABILITY_SHIFT;
+
+    buffer = _xzalloc(ITS_CMD_QUEUE_SZ, PAGE_SIZE);
+    if ( !buffer )
+        return NULL;
+
+    reg = attr | BIT_ULL(63) | (virt_to_maddr(buffer) & GENMASK(51, 12));
+    reg |= ((ITS_CMD_QUEUE_SZ / PAGE_SIZE) - 1) & GITS_CBASER_SIZE_MASK;
+    writeq_relaxed(reg, cbasereg);
+
+    return buffer;
+}
+
 static int its_map_baser(void __iomem *basereg, uint64_t regc, int nr_items)
 {
     uint64_t attr;
@@ -148,6 +171,10 @@ int gicv3_its_init(struct host_its *hw_its)
         }
     }
 
+    hw_its->cmd_buf = its_map_cbaser(hw_its->its_base + GITS_CBASER);
+    if ( !hw_its->cmd_buf )
+        return -ENOMEM;
+
     return 0;
 }
 
diff --git a/xen/include/asm-arm/gic-its.h b/xen/include/asm-arm/gic-its.h
index 26b0584..e0fded8 100644
--- a/xen/include/asm-arm/gic-its.h
+++ b/xen/include/asm-arm/gic-its.h
@@ -61,6 +61,8 @@
                                         (31UL << GITS_BASER_ENTRY_SIZE_SHIFT) 
|\
                                         GITS_BASER_INDIRECT)
 
+#define GITS_CBASER_SIZE_MASK           0xff
+
 #ifndef __ASSEMBLY__
 #include <xen/device_tree.h>
 
@@ -71,6 +73,7 @@ struct host_its {
     paddr_t addr;
     paddr_t size;
     void __iomem *its_base;
+    void *cmd_buf;
 };
 
 extern struct list_head host_its_list;
-- 
2.9.0


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