# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1271954636 -3600
# Node ID 2b97855a629f1d79e1d075a6d2a8b569018b2094
# Parent a7947fd90328287dd097294b241753063c858597
console: Make initial static console buffer __initdata.
The previous scheme --- freeing an area of BSS --- did not interact
nicely with device passthrough as IOMMU will not have any Xen BSS area
in guest device pagetables. Hence if the freed BSS space gets
allocated to a guest, DMAs to guest's own memory can fail.
The simple solution here is to always free the static buffer at end of
boot (initmem is specially handled for IOMMUs) and require a
dynamically-allocated buffer always to be created.
Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx>
---
xen/drivers/char/console.c | 31 ++++++++++---------------------
1 files changed, 10 insertions(+), 21 deletions(-)
diff -r a7947fd90328 -r 2b97855a629f xen/drivers/char/console.c
--- a/xen/drivers/char/console.c Thu Apr 22 09:44:29 2010 +0100
+++ b/xen/drivers/char/console.c Thu Apr 22 17:43:56 2010 +0100
@@ -66,11 +66,7 @@ size_param("conring_size", opt_conring_s
#define _CONRING_SIZE 16384
#define CONRING_IDX_MASK(i) ((i)&(conring_size-1))
-static char
-#if _CONRING_SIZE >= PAGE_SIZE
- __attribute__((__section__(".bss.page_aligned"), __aligned__(PAGE_SIZE)))
-#endif
- _conring[_CONRING_SIZE];
+static char __initdata _conring[_CONRING_SIZE];
static char *__read_mostly conring = _conring;
static uint32_t __read_mostly conring_size = _CONRING_SIZE;
static uint32_t conringc, conringp;
@@ -597,25 +593,20 @@ void __init console_init_postirq(void)
void __init console_init_postirq(void)
{
char *ring;
- unsigned int i;
+ unsigned int i, order;
serial_init_postirq();
if ( !opt_conring_size )
opt_conring_size = num_present_cpus() << (9 + xenlog_lower_thresh);
- /* Round size down to a power of two. */
- while ( opt_conring_size & (opt_conring_size - 1) )
- opt_conring_size &= opt_conring_size - 1;
- if ( opt_conring_size < conring_size )
- return;
-
- ring = alloc_xenheap_pages(get_order_from_bytes(opt_conring_size), 0);
- if ( ring == NULL )
- {
- printk("Unable to allocate console ring of %u bytes.\n",
- opt_conring_size);
- return;
- }
+
+ order = get_order_from_bytes(max(opt_conring_size, conring_size));
+ while ( (ring = alloc_xenheap_pages(order, 0)) == NULL )
+ {
+ BUG_ON(order == 0);
+ order--;
+ }
+ opt_conring_size = PAGE_SIZE << order;
spin_lock_irq(&console_lock);
for ( i = conringc ; i != conringp; i++ )
@@ -626,8 +617,6 @@ void __init console_init_postirq(void)
spin_unlock_irq(&console_lock);
printk("Allocated console ring of %u KiB.\n", opt_conring_size >> 10);
-
- init_xenheap_pages(__pa(_conring), __pa(_conring + _CONRING_SIZE));
}
void __init console_endboot(void)
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