[RFC][PATCH 10/12] x86,intel_iommu: Replace cmpxchg_double()

Peter Zijlstra
2022-12-19T15:46:09Z

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
drivers/iommu/intel/irq_remapping.c | 8 --
include/linux/dmar.h | 125 +++++++++++++++++++-----------------
2 files changed, 68 insertions(+), 65 deletions(-)

--- a/drivers/iommu/intel/irq_remapping.c
+++ b/drivers/iommu/intel/irq_remapping.c
@@ -174,18 +174,14 @@ static int modify_irte(struct irq_2_iomm
irte = &iommu->ir_table->base[index];

if ((irte->pst == 1) || (irte_modified->pst == 1)) {
- bool ret;
-
- ret = cmpxchg_double(&irte->low, &irte->high,
- irte->low, irte->high,
- irte_modified->low, irte_modified->high);
/*
* 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);
+ u128 old = irte->irte;
+ WARN_ON(!try_cmpxchg128(&irte->irte, &old, irte_modified->irte));
} else {
WRITE_ONCE(irte->low, irte_modified->low);
WRITE_ONCE(irte->high, irte_modified->high);
--- a/include/linux/dmar.h
+++ b/include/linux/dmar.h
@@ -201,67 +201,74 @@ static inline void detect_intel_iommu(vo

struct irte {
union {
- /* Shared between remapped and posted mode*/
struct {
- __u64 present : 1, /* 0 */
- fpd : 1, /* 1 */
- __res0 : 6, /* 2 - 6 */
- avail : 4, /* 8 - 11 */
- __res1 : 3, /* 12 - 14 */
- pst : 1, /* 15 */
- vector : 8, /* 16 - 23 */
- __res2 : 40; /* 24 - 63 */
+ union {
+ /* Shared between remapped and posted mode*/
+ struct {
+ __u64 present : 1, /* 0 */
+ fpd : 1, /* 1 */
+ __res0 : 6, /* 2 - 6 */
+ avail : 4, /* 8 - 11 */
+ __res1 : 3, /* 12 - 14 */
+ pst : 1, /* 15 */
+ vector : 8, /* 16 - 23 */
+ __res2 : 40; /* 24 - 63 */
+ };
+
+ /* Remapped mode */
+ struct {
+ __u64 r_present : 1, /* 0 */
+ r_fpd : 1, /* 1 */
+ dst_mode : 1, /* 2 */
+ redir_hint : 1, /* 3 */
+ trigger_mode : 1, /* 4 */
+ dlvry_mode : 3, /* 5 - 7 */
+ r_avail : 4, /* 8 - 11 */
+ r_res0 : 4, /* 12 - 15 */
+ r_vector : 8, /* 16 - 23 */
+ r_res1 : 8, /* 24 - 31 */
+ dest_id : 32; /* 32 - 63 */
+ };
+
+ /* Posted mode */
+ struct {
+ __u64 p_present : 1, /* 0 */
+ p_fpd : 1, /* 1 */
+ p_res0 : 6, /* 2 - 7 */
+ p_avail : 4, /* 8 - 11 */
+ p_res1 : 2, /* 12 - 13 */
+ p_urgent : 1, /* 14 */
+ p_pst : 1, /* 15 */
+ p_vector : 8, /* 16 - 23 */
+ p_res2 : 14, /* 24 - 37 */
+ pda_l : 26; /* 38 - 63 */
+ };
+ __u64 low;
+ };
+
+ union {
+ /* Shared between remapped and posted mode*/
+ struct {
+ __u64 sid : 16, /* 64 - 79 */
+ sq : 2, /* 80 - 81 */
+ svt : 2, /* 82 - 83 */
+ __res3 : 44; /* 84 - 127 */
+ };
+
+ /* Posted mode*/
+ struct {
+ __u64 p_sid : 16, /* 64 - 79 */
+ p_sq : 2, /* 80 - 81 */
+ p_svt : 2, /* 82 - 83 */
+ p_res3 : 12, /* 84 - 95 */
+ pda_h : 32; /* 96 - 127 */
+ };
+ __u64 high;
+ };
};
-
- /* Remapped mode */
- struct {
- __u64 r_present : 1, /* 0 */
- r_fpd : 1, /* 1 */
- dst_mode : 1, /* 2 */
- redir_hint : 1, /* 3 */
- trigger_mode : 1, /* 4 */
- dlvry_mode : 3, /* 5 - 7 */
- r_avail : 4, /* 8 - 11 */
- r_res0 : 4, /* 12 - 15 */
- r_vector : 8, /* 16 - 23 */
- r_res1 : 8, /* 24 - 31 */
- dest_id : 32; /* 32 - 63 */
- };
-
- /* Posted mode */
- struct {
- __u64 p_present : 1, /* 0 */
- p_fpd : 1, /* 1 */
- p_res0 : 6, /* 2 - 7 */
- p_avail : 4, /* 8 - 11 */
- p_res1 : 2, /* 12 - 13 */
- p_urgent : 1, /* 14 */
- p_pst : 1, /* 15 */
- p_vector : 8, /* 16 - 23 */
- p_res2 : 14, /* 24 - 37 */
- pda_l : 26; /* 38 - 63 */
- };
- __u64 low;
- };
-
- union {
- /* Shared between remapped and posted mode*/
- struct {
- __u64 sid : 16, /* 64 - 79 */
- sq : 2, /* 80 - 81 */
- svt : 2, /* 82 - 83 */
- __res3 : 44; /* 84 - 127 */
- };
-
- /* Posted mode*/
- struct {
- __u64 p_sid : 16, /* 64 - 79 */
- p_sq : 2, /* 80 - 81 */
- p_svt : 2, /* 82 - 83 */
- p_res3 : 12, /* 84 - 95 */
- pda_h : 32; /* 96 - 127 */
- };
- __u64 high;
+#ifdef CONFIG_IRQ_REMAP
+ __u128 irte;
+#endif
};
};