x86,amd_iommu: Replace cmpxchg_double()

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Vasant Hegde <vasant.hegde@amd.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20230531132323.788955257@infradead.org

diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
index 2ddbda3..ab8aa8f 100644 (file)
--- a/drivers/iommu/amd/amd_iommu_types.h
+++ b/drivers/iommu/amd/amd_iommu_types.h
@@ -986,8 +986,13 @@ union irte_ga_hi {
 };
 
 struct irte_ga {
-       union irte_ga_lo lo;
-       union irte_ga_hi hi;
+       union {
+               struct {
+                       union irte_ga_lo lo;
+                       union irte_ga_hi hi;
+               };
+               u128 irte;
+       };
 };
 
 struct irq_2_irte {

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 4a31464..1e9f85e 100644 (file)
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3003,10 +3003,10 @@ out:
 static int modify_irte_ga(struct amd_iommu *iommu, u16 devid, int index,
                          struct irte_ga *irte, struct amd_ir_data *data)
 {
-       bool ret;
        struct irq_remap_table *table;
-       unsigned long flags;
        struct irte_ga *entry;
+       unsigned long flags;
+       u128 old;
 
        table = get_irq_table(iommu, devid);
        if (!table)
@@ -3017,16 +3017,14 @@ static int modify_irte_ga(struct amd_iommu *iommu, u16 devid, int index,
        entry = (struct irte_ga *)table->table;
        entry = &entry[index];
 
-       ret = cmpxchg_double(&entry->lo.val, &entry->hi.val,
-                            entry->lo.val, entry->hi.val,
-                            irte->lo.val, irte->hi.val);
        /*
         * We use cmpxchg16 to atomically update the 128-bit IRTE,
         * and it cannot be updated by the hardware or other processors
         * behind us, so the return value of cmpxchg16 should be the
         * same as the old value.
         */
-       WARN_ON(!ret);
+       old = entry->irte;
+       WARN_ON(!try_cmpxchg128(&entry->irte, &old, irte->irte));
 
        if (data)
                data->ref = entry;