[xen master] xen/arm: its: initialize host LPI state before activating ITSes

[patchbot@xxxxxxx]

commit b5c1b941559a56a9a9cc10f5faab0c88f18057d3
Author:     Mykola Kvach <mykola_kvach@xxxxxxxx>
AuthorDate: Tue Sep 29 22:02:10 2026 +0300
Commit:     Michal Orzel <michal.orzel@xxxxxxx>
CommitDate: Mon Oct 26 09:01:40 2026 +0100

    xen/arm: its: initialize host LPI state before activating ITSes
    
    The boot CPU pending table must use the memory attributes selected by
    ITS quirks. gicv3_lpi_init_host_lpis() is therefore called after
    gicv3_its_init(). However, gicv3_its_init() also programs and enables
    each ITS before host LPI state is allocated. No ITS commands are
    submitted at that point, but this ordering relies on that implementation
    detail.
    
    Split per-ITS initialization into preparation and activation phases.
    First map and disable every ITS and collect its quirks. Then initialize
    host LPI state. Only after that, allocate and program the ITS tables and
    command queue, and enable each ITS.
    
    The subsequent gicv3_cpu_init() sequence remains unchanged: it programs
    the Redistributor LPI tables, enables LPIs, and then submits the first
    MAPC and SYNC commands.
    
    Drop the now unreachable stub for gicv3_lpi_init_host_lpis().
    
    Suggested-by: Julien Grall <julien@xxxxxxx>
    Signed-off-by: Mykola Kvach <mykola_kvach@xxxxxxxx>
    Reviewed-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
    Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>
---
 xen/arch/arm/gic-v3-its.c             | 32 +++++++++++++++++++++++++++-----
 xen/arch/arm/gic-v3.c                 | 15 ++-------------
 xen/arch/arm/include/asm/gic_v3_its.h |  9 ++-------
 3 files changed, 31 insertions(+), 25 deletions(-)

diff --git a/xen/arch/arm/gic-v3-its.c b/xen/arch/arm/gic-v3-its.c
index 325835b0ad..511e49a116 100644
--- a/xen/arch/arm/gic-v3-its.c
+++ b/xen/arch/arm/gic-v3-its.c
@@ -11,6 +11,7 @@
 #include <xen/lib.h>
 #include <xen/delay.h>
 #include <xen/iocap.h>
+#include <xen/init.h>
 #include <xen/libfdt/libfdt.h>
 #include <xen/mm.h>
 #include <xen/rbtree.h>
@@ -549,10 +550,9 @@ static int gicv3_disable_its(struct host_its *hw_its)
     return -ETIMEDOUT;
 }
 
-static int gicv3_its_init_single_its(struct host_its *hw_its)
+static int __init gicv3_its_prepare_single_its(struct host_its *hw_its)
 {
-    uint64_t reg;
-    int i, ret;
+    int ret;
 
     hw_its->its_base = ioremap_nocache(hw_its->addr, hw_its->size);
     if ( !hw_its->its_base )
@@ -564,6 +564,14 @@ static int gicv3_its_init_single_its(struct host_its 
*hw_its)
 
     gicv3_its_enable_quirks(hw_its);
 
+    return 0;
+}
+
+static int __init gicv3_its_init_single_its(struct host_its *hw_its)
+{
+    uint64_t reg;
+    int i, ret;
+
     reg = readq_relaxed(hw_its->its_base + GITS_TYPER);
     hw_its->devid_bits = GITS_TYPER_DEVICE_ID_BITS(reg);
     hw_its->evid_bits = GITS_TYPER_EVENT_ID_BITS(reg);
@@ -1189,7 +1197,7 @@ static void gicv3_its_acpi_init(void)
 
 #endif
 
-int gicv3_its_init(void)
+int __init gicv3_its_init(unsigned int host_lpi_bits)
 {
     struct host_its *hw_its;
     int ret;
@@ -1199,15 +1207,29 @@ int gicv3_its_init(void)
     else
         gicv3_its_acpi_init();
 
+    if ( list_empty(&host_its_list) )
+        return 0;
+
     list_for_each_entry(hw_its, &host_its_list, entry)
     {
-        ret = gicv3_its_init_single_its(hw_its);
+        ret = gicv3_its_prepare_single_its(hw_its);
         if ( ret )
             return ret;
     }
 
     gicv3_its_validate_quirks();
 
+    ret = gicv3_lpi_init_host_lpis(host_lpi_bits);
+    if ( ret )
+        return ret;
+
+    list_for_each_entry(hw_its, &host_its_list, entry)
+    {
+        ret = gicv3_its_init_single_its(hw_its);
+        if ( ret )
+            return ret;
+    }
+
     return 0;
 }
 
diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
index 23a4497a30..cca49d2a2a 100644
--- a/xen/arch/arm/gic-v3.c
+++ b/xen/arch/arm/gic-v3.c
@@ -2037,20 +2037,9 @@ static int __init gicv3_init(void)
 
     if ( gic_dist_supports_lpis() )
     {
-        res = gicv3_its_init();
+        res = gicv3_its_init(intid_bits);
         if ( res )
-            panic("GICv3: ITS: initialization failed: %d\n", res);
-
-        /*
-         * Host LPI allocation uses ITS-derived memory attributes, so defer it
-         * until after gicv3_its_init() has discovered ITS workarounds.
-         */
-        if ( gicv3_its_host_has_its() )
-        {
-            res = gicv3_lpi_init_host_lpis(intid_bits);
-            if ( res )
-                panic("GICv3: LPI initialization failed: %d\n", res);
-        }
+            panic("GICv3: ITS/LPI initialization failed: %d\n", res);
     }
 
     res = gicv3_cpu_init();
diff --git a/xen/arch/arm/include/asm/gic_v3_its.h 
b/xen/arch/arm/include/asm/gic_v3_its.h
index 02c083f210..5ab4c7a8c3 100644
--- a/xen/arch/arm/include/asm/gic_v3_its.h
+++ b/xen/arch/arm/include/asm/gic_v3_its.h
@@ -156,7 +156,7 @@ int gicv3_lpi_init_rdist(void __iomem * rdist_base);
 
 /* Initialize the host structures for LPIs and the host ITSes. */
 int gicv3_lpi_init_host_lpis(unsigned int host_lpi_bits);
-int gicv3_its_init(void);
+int gicv3_its_init(unsigned int host_lpi_bits);
 
 /* Store the physical address and ID for each redistributor as read from DT. */
 void gicv3_set_redist_address(paddr_t address, unsigned int redist_id);
@@ -240,12 +240,7 @@ static inline int gicv3_lpi_init_rdist(void __iomem * 
rdist_base)
     return -ENODEV;
 }
 
-static inline int gicv3_lpi_init_host_lpis(unsigned int host_lpi_bits)
-{
-    return 0;
-}
-
-static inline int gicv3_its_init(void)
+static inline int gicv3_its_init(unsigned int host_lpi_bits)
 {
     return 0;
 }
--
generated by git-patchbot for /home/xen/git/xen.git#master