Hi,
On 26/04/2022 15:01, Jan Beulich wrote:
On 25.04.2022 15:28, David Vrabel wrote:
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -162,6 +162,13 @@
static char __initdata opt_badpage[100] = "";
string_param("badpage", opt_badpage);
+/*
+ * Heap allocations may need TLB flushes which require IRQs to be
+ * enabled (except when only 1 PCPU is online).
+ */
+#define ASSERT_ALLOC_CONTEXT() \
+ ASSERT(!in_irq() && (local_irq_is_enabled() || num_online_cpus() <= 1))
At least one of these tightened assertions triggers on Arm, as per the
most recent smoke flight. I'm going to revert this for the time being.
From the serial console [1]:
(XEN) Xen call trace:
(XEN) [<0022a510>] alloc_xenheap_pages+0x120/0x150 (PC)
(XEN) [<00000000>] 00000000 (LR)
(XEN) [<002736ac>] arch/arm/mm.c#xen_pt_update+0x144/0x6e4
(XEN) [<002740d4>] map_pages_to_xen+0x10/0x20
(XEN) [<00236864>] __vmap+0x400/0x4a4
(XEN) [<0026aee8>]
arch/arm/alternative.c#__apply_alternatives_multi_stop+0x144/0x1ec
(XEN) [<0022fe40>] stop_machine_run+0x23c/0x300
(XEN) [<002c40c4>] apply_alternatives_all+0x34/0x5c
(XEN) [<002ce3e8>] start_xen+0xcb8/0x1024
(XEN) [<00200068>] arch/arm/arm32/head.o#primary_switched+0xc/0x1c
So we need to move out the vmap() from the
__apply_alternatives_multi_stop() to apply_alternatives_all().
The patch below (only compile tested so far) should do the job. I will
do further testing and confirm there are no other issue on Arm.
diff --git a/xen/arch/arm/alternative.c b/xen/arch/arm/alternative.c
index 237c4e564209..8004fc8a7d1a 100644
--- a/xen/arch/arm/alternative.c
+++ b/xen/arch/arm/alternative.c
@@ -170,7 +170,7 @@ static int __apply_alternatives(const struct
alt_region *region,
* We might be patching the stop_machine state machine, so implement a
* really simple polling protocol here.
*/
-static int __apply_alternatives_multi_stop(void *unused)
+static int __apply_alternatives_multi_stop(void *xenmap)
{
static int patched = 0;
@@ -185,22 +185,9 @@ static int __apply_alternatives_multi_stop(void
*unused)
{
int ret;
struct alt_region region;
- mfn_t xen_mfn = virt_to_mfn(_start);
- paddr_t xen_size = _end - _start;
- unsigned int xen_order = get_order_from_bytes(xen_size);
- void *xenmap;
BUG_ON(patched);
- /*
- * The text and inittext section are read-only. So re-map Xen to
- * be able to patch the code.
- */
- xenmap = __vmap(&xen_mfn, 1U << xen_order, 1, 1, PAGE_HYPERVISOR,
- VMAP_DEFAULT);
- /* Re-mapping Xen is not expected to fail during boot. */
- BUG_ON(!xenmap);
-
region.begin = __alt_instructions;
region.end = __alt_instructions_end;
@@ -208,8 +195,6 @@ static int __apply_alternatives_multi_stop(void *unused)
/* The patching is not expected to fail during boot. */
BUG_ON(ret != 0);
- vunmap(xenmap);
-
/* Barriers provided by the cache flushing */
write_atomic(&patched, 1);
}
@@ -224,14 +209,29 @@ static int __apply_alternatives_multi_stop(void
*unused)
void __init apply_alternatives_all(void)
{
int ret;
+ mfn_t xen_mfn = virt_to_mfn(_start);
+ paddr_t xen_size = _end - _start;
+ unsigned int xen_order = get_order_from_bytes(xen_size);
+ void *xenmap;
ASSERT(system_state != SYS_STATE_active);
+ /*
+ * The text and inittext section are read-only. So re-map Xen to
+ * be able to patch the code.
+ */
+ xenmap = __vmap(&xen_mfn, 1U << xen_order, 1, 1, PAGE_HYPERVISOR,
+ VMAP_DEFAULT);
+ /* Re-mapping Xen is not expected to fail during boot. */
+ BUG_ON(!xenmap);
+
/* better not try code patching on a live SMP system */
ret = stop_machine_run(__apply_alternatives_multi_stop, NULL,
NR_CPUS);
/* stop_machine_run should never fail at this stage of the boot */
BUG_ON(ret);
+
+ vunmap(xenmap);
}
int apply_alternatives(const struct alt_instr *start, const struct
alt_instr *end)
Cheers,
[1]
http://logs.test-lab.xenproject.org/osstest/logs/169729/test-armhf-armhf-xl/info.html
Jan
--
Julien Grall
