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Re: [Xen-devel] [PATCH 06/28] ARM: GICv3 ITS: introduce ITS command handling



Hi Andre,

Continuing the review where I left it yesterday.

On 30/01/2017 18:31, Andre Przywara wrote:

[...]

+/* Wait for an ITS to become quiescient (all ITS operations completed). */
+static int gicv3_its_wait_quiescient(struct host_its *hw_its)
+{
+    uint32_t reg;
+    s_time_t deadline = NOW() + MILLISECS(1000);
+
+    reg = readl_relaxed(hw_its->its_base + GITS_CTLR);
+    if ( (reg & (GITS_CTLR_QUIESCENT | GITS_CTLR_ENABLE)) == 
GITS_CTLR_QUIESCENT )

It would be clearer if you rewrite this:

 (reg & GITS_CTLR_QUIESCENT) && !(reg & GITS_CTLR_ENABLE).

+        return 0;
+
+    writel_relaxed(reg & ~GITS_CTLR_ENABLE, hw_its->its_base + GITS_CTLR);

It feels a bit odd to disable the ITS in a function containing "wait" in the name. You may want to rename the function to reflect the behavior.

+
+    do {
+        reg = readl_relaxed(hw_its->its_base + GITS_CTLR);
+        if ( reg & GITS_CTLR_QUIESCENT )
+            return 0;
+
+        cpu_relax();
+        udelay(1);
+    } while ( NOW() <= deadline );
+
+    dprintk(XENLOG_ERR, "ITS not quiescient\n");
+    return -ETIMEDOUT;
+}
+
 static unsigned int max_its_device_bits = CONFIG_MAX_PHYS_ITS_DEVICE_BITS;
 integer_param("max_its_device_bits", max_its_device_bits);

 int gicv3_its_init(struct host_its *hw_its)
 {
     uint64_t reg;
-    int i;
+    int i, ret;

     hw_its->its_base = ioremap_nocache(hw_its->addr, hw_its->size);
     if ( !hw_its->its_base )
         return -ENOMEM;

+    ret = gicv3_its_wait_quiescient(hw_its);
+    if ( ret )
+        return ret;
+
+    reg = readq_relaxed(hw_its->its_base + GITS_TYPER);
+    if ( reg & GITS_TYPER_PTA )
+        hw_its->flags |= HOST_ITS_USES_PTA;
+
     for ( i = 0; i < GITS_BASER_NR_REGS; i++ )
     {
         void __iomem *basereg = hw_its->its_base + GITS_BASER0 + i * 8;
@@ -196,6 +322,20 @@ int gicv3_its_init(struct host_its *hw_its)
         return -ENOMEM;
     writeq_relaxed(0, hw_its->its_base + GITS_CWRITER);


[...]

diff --git a/xen/arch/arm/gic-v3-lpi.c b/xen/arch/arm/gic-v3-lpi.c
index e2fc901..5911b91 100644
--- a/xen/arch/arm/gic-v3-lpi.c
+++ b/xen/arch/arm/gic-v3-lpi.c
@@ -30,11 +30,31 @@ static struct {
     unsigned int host_lpi_bits;
 } lpi_data;

+/* Physical redistributor address */
+static DEFINE_PER_CPU(paddr_t, redist_addr);
+/* Redistributor ID */
+static DEFINE_PER_CPU(int, redist_id);

s/int/unsigned int/

 /* Pending table for each redistributor */
 static DEFINE_PER_CPU(void *, pending_table);

Rather than defining 3 per-cpu variables, could we merge all in a single structure?


 #define MAX_PHYS_LPIS   (BIT_ULL(lpi_data.host_lpi_bits) - LPI_OFFSET)

+/* Stores this redistributor's physical address and ID in a per-CPU variable */
+void gicv3_set_redist_address(paddr_t address, int redist_id)

s/int/unsigned int/

+{
+    this_cpu(redist_addr) = address;
+    this_cpu(redist_id) = redist_id;
+}
+
+/* Returns a redistributor's ID (either as an address or as an ID) */
+uint64_t gicv3_get_redist_address(int cpu, bool use_pta)

s/int/unsigned int/

+{
+    if ( use_pta )
+        return per_cpu(redist_addr, cpu) & GENMASK(51, 16);
+    else
+        return per_cpu(redist_id, cpu) << 16;

What if the function is called before the CPU has been setup? If it cannot happen, please document it.

+}
+
 uint64_t gicv3_lpi_allocate_pendtable(void)
 {
     uint64_t reg;
diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
index 440c079..5f825a6 100644
--- a/xen/arch/arm/gic-v3.c
+++ b/xen/arch/arm/gic-v3.c
@@ -644,7 +644,7 @@ static int gicv3_rdist_init_lpis(void __iomem * rdist_base)
         return -ENOMEM;
     writeq_relaxed(table_reg, rdist_base + GICR_PROPBASER);

-    return 0;
+    return gicv3_its_setup_collection(smp_processor_id());
 }

 static int __init gicv3_populate_rdist(void)
@@ -692,7 +692,21 @@ static int __init gicv3_populate_rdist(void)

                 if ( typer & GICR_TYPER_PLPIS )
                 {
-                    int ret;
+                    paddr_t rdist_addr;
+                    int procnum, ret;

procnum should be unsigned.

+
+                    rdist_addr = gicv3.rdist_regions[i].base;
+                    rdist_addr += ptr - gicv3.rdist_regions[i].map_base;
+                    procnum = (typer & GICR_TYPER_PROC_NUM_MASK);
+                    procnum >>= GICR_TYPER_PROC_NUM_SHIFT;
+
+                    /*
+                     * The ITS refers to redistributors either by their 
physical
+                     * address or by their ID. Determine those two values and
+                     * let the ITS code store them in per host CPU variables to
+                     * later be able to address those redistributors.
+                     */

This comment does not look useful and is misleading as the code to get/set the redistributor information is living in gic-v3-lpi.c and not gic-v3-its.c.

+                    gicv3_set_redist_address(rdist_addr, procnum);

                     ret = gicv3_rdist_init_lpis(ptr);
                     if ( ret && ret != -ENODEV )
diff --git a/xen/include/asm-arm/gic_v3_defs.h 
b/xen/include/asm-arm/gic_v3_defs.h
index b307322..878bae2 100644
--- a/xen/include/asm-arm/gic_v3_defs.h
+++ b/xen/include/asm-arm/gic_v3_defs.h
@@ -101,6 +101,8 @@
 #define GICR_TYPER_PLPIS             (1U << 0)
 #define GICR_TYPER_VLPIS             (1U << 1)
 #define GICR_TYPER_LAST              (1U << 4)
+#define GICR_TYPER_PROC_NUM_SHIFT    8
+#define GICR_TYPER_PROC_NUM_MASK     (0xffff << GICR_TYPER_PROC_NUM_SHIFT)

 /* For specifying the inner cacheability type only */
 #define GIC_BASER_CACHE_nCnB         0ULL
diff --git a/xen/include/asm-arm/gic_v3_its.h b/xen/include/asm-arm/gic_v3_its.h
index ff5572f..8288185 100644
--- a/xen/include/asm-arm/gic_v3_its.h
+++ b/xen/include/asm-arm/gic_v3_its.h
@@ -40,6 +40,9 @@
 #define GITS_CTLR_QUIESCENT             BIT(31)
 #define GITS_CTLR_ENABLE                BIT(0)

+#define GITS_TYPER_PTA                  BIT_ULL(19)
+#define GITS_TYPER_IDBITS_SHIFT         8
+
 #define GITS_IIDR_VALUE                 0x34c

 #define GITS_BASER_INDIRECT             BIT_ULL(62)
@@ -67,10 +70,27 @@

 #define GITS_CBASER_SIZE_MASK           0xff

+/* ITS command definitions */
+#define ITS_CMD_SIZE                    32
+
+#define GITS_CMD_MOVI                   0x01
+#define GITS_CMD_INT                    0x03
+#define GITS_CMD_CLEAR                  0x04
+#define GITS_CMD_SYNC                   0x05
+#define GITS_CMD_MAPD                   0x08
+#define GITS_CMD_MAPC                   0x09
+#define GITS_CMD_MAPTI                  0x0a
+#define GITS_CMD_MAPI                   0x0b
+#define GITS_CMD_INV                    0x0c
+#define GITS_CMD_INVALL                 0x0d
+#define GITS_CMD_MOVALL                 0x0e
+#define GITS_CMD_DISCARD                0x0f
+
 #ifndef __ASSEMBLY__
 #include <xen/device_tree.h>

 #define HOST_ITS_FLUSH_CMD_QUEUE        (1U << 0)
+#define HOST_ITS_USES_PTA               (1U << 1)

 /* data structure for each hardware ITS */
 struct host_its {
@@ -79,6 +99,7 @@ struct host_its {
     paddr_t addr;
     paddr_t size;
     void __iomem *its_base;
+    spinlock_t cmd_lock;

I was expecting to see a code to initialize the spinlock. So please initialize the spinlock.

     void *cmd_buf;
     unsigned int flags;
 };

Cheers,


--
Julien Grall

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