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Re: [PATCH] xen/device-tree: Allow exact match for overlapping regions
Hi Luca,
On 06/11/2024 13:41, Luca Fancellu wrote:
There are some cases where the device tree exposes a memory range
in both /memreserve/ and reserved-memory node, in this case the
current code will stop Xen to boot since it will find that the
latter range is clashing with the already recorded /memreserve/
ranges.
Furthermore, u-boot lists boot modules ranges, such as ramdisk,
in the /memreserve/ part and even in this case this will prevent
Xen to boot since it will see that the module memory range that
it is going to add in 'add_boot_module' clashes with a /memreserve/
range.
When Xen populate the data structure that tracks the memory ranges,
it also adds a memory type described in 'enum membank_type', so
in order to fix this behavior, allow the 'check_reserved_regions_overlap'
function to check for exact memory range match given a specific memory
type; allowing reserved-memory node ranges and boot modules to have an
exact match with ranges from /memreserve/.
While there, set a type for the memory recorded during ACPI boot.
I am a bit confused which you mention only ACPI boot. Isn't the path
also used when booting using Device-Tree?
Fixes: 53dc37829c31 ("xen/arm: Add DT reserve map regions to
bootinfo.reserved_mem")
Reported-by: Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>
Reported-by: Grygorii Strashko <grygorii_strashko@xxxxxxxx>
Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
---
I tested this patch adding the same range in a /memreserve/ entry and
/reserved-memory node, and by letting u-boot pass a ramdisk.
I've also tested that a configuration running static shared memory still works
fine.
---
xen/arch/arm/efi/efi-boot.h | 3 +-
xen/arch/arm/static-shmem.c | 2 +-
xen/common/device-tree/bootfdt.c | 9 +++++-
xen/common/device-tree/bootinfo.c | 48 ++++++++++++++++++++++++-------
xen/include/xen/bootfdt.h | 9 +++++-
5 files changed, 57 insertions(+), 14 deletions(-)
diff --git a/xen/arch/arm/efi/efi-boot.h b/xen/arch/arm/efi/efi-boot.h
index 199f5260229d..d35c991c856f 100644
--- a/xen/arch/arm/efi/efi-boot.h
+++ b/xen/arch/arm/efi/efi-boot.h
@@ -167,13 +167,14 @@ static bool __init meminfo_add_bank(struct membanks *mem,
if ( mem->nr_banks >= mem->max_banks )
return false;
#ifdef CONFIG_ACPI
- if ( check_reserved_regions_overlap(start, size) )
+ if ( check_reserved_regions_overlap(start, size, MEMBANK_NONE) )
return false;
#endif
bank = &mem->bank[mem->nr_banks];
bank->start = start;
bank->size = size;
+ bank->type = MEMBANK_DEFAULT;
mem->nr_banks++;
diff --git a/xen/arch/arm/static-shmem.c b/xen/arch/arm/static-shmem.c
index aa80756c3ca5..149ed4b0a5ba 100644
--- a/xen/arch/arm/static-shmem.c
+++ b/xen/arch/arm/static-shmem.c
@@ -696,7 +696,7 @@ int __init process_shm_node(const void *fdt, int node,
uint32_t address_cells,
if (i < mem->max_banks)
{
if ( (paddr != INVALID_PADDR) &&
- check_reserved_regions_overlap(paddr, size) )
+ check_reserved_regions_overlap(paddr, size, MEMBANK_NONE) )
return -EINVAL;
/* Static shared memory shall be reserved from any other use. */
diff --git a/xen/common/device-tree/bootfdt.c b/xen/common/device-tree/bootfdt.c
index 927f59c64b0d..fb3a6ab95a22 100644
--- a/xen/common/device-tree/bootfdt.c
+++ b/xen/common/device-tree/bootfdt.c
@@ -176,8 +176,15 @@ static int __init device_tree_get_meminfo(const void *fdt,
int node,
for ( i = 0; i < banks && mem->nr_banks < mem->max_banks; i++ )
{
device_tree_get_reg(&cell, address_cells, size_cells, &start, &size);
+ /*
+ * Some valid device trees, such as those generated by OpenPOWER
+ * skiboot firmware, expose all reserved memory regions in the
+ * FDT memory reservation block AND in the reserved-memory node which
+ * has already been parsed. Thus, any matching overlaps in the
+ * reserved_mem banks should be ignored.
+ */
if ( mem == bootinfo_get_reserved_mem() &&
- check_reserved_regions_overlap(start, size) )
+ check_reserved_regions_overlap(start, size, MEMBANK_FDT_RESVMEM) )
return -EINVAL;
/* Some DT may describe empty bank, ignore them */
if ( !size )
diff --git a/xen/common/device-tree/bootinfo.c
b/xen/common/device-tree/bootinfo.c
index f2e6a1145b7c..05038075e835 100644
--- a/xen/common/device-tree/bootinfo.c
+++ b/xen/common/device-tree/bootinfo.c
@@ -99,7 +99,8 @@ static void __init dt_unreserved_regions(paddr_t s, paddr_t e,
*/
static bool __init meminfo_overlap_check(const struct membanks *mem,
paddr_t region_start,
- paddr_t region_size)
+ paddr_t region_size,
+ enum membank_type allow_match_type)
Looking at the callers, you only seem to pass MEMBANK_FDT_RESVMEM or
MEMBANK_NONE. So I wonder whether it actually make sense to introduce
MEMBANK_NONE. Wouldn't it be better to have a boolean indicating whether
we are looking for FDT_RESVMEM?
{
paddr_t bank_start = INVALID_PADDR, bank_end = 0;
paddr_t region_end = region_start + region_size;
@@ -113,12 +114,16 @@ static bool __init meminfo_overlap_check(const struct
membanks *mem,
if ( INVALID_PADDR == bank_start || region_end <= bank_start ||
region_start >= bank_end )
continue;
- else
- {
- printk("Region: [%#"PRIpaddr", %#"PRIpaddr") overlapping with bank[%u]:
[%#"PRIpaddr", %#"PRIpaddr")\n",
- region_start, region_end, i, bank_start, bank_end);
- return true;
- }
+
+ if ( (allow_match_type != MEMBANK_NONE) &&
+ (region_start == bank_start) && (region_end == bank_end) &&
Why is this only an exact match?
+ (allow_match_type == mem->bank[i].type) )
+ continue;
+
+ printk("Region: [%#"PRIpaddr", %#"PRIpaddr") overlapping with bank[%u]:
[%#"PRIpaddr", %#"PRIpaddr")\n",
+ region_start, region_end, i, bank_start, bank_end);
+ return true;
+
}
return false;
@@ -169,9 +174,14 @@ void __init fw_unreserved_regions(paddr_t s, paddr_t e,
* with the existing reserved memory regions defined in bootinfo.
* Return true if the input physical address range is overlapping with any
* existing reserved memory regions, otherwise false.
+ * The 'allow_match_type' parameter can be used to allow exact match of a
+ * region with another memory region already recorded, but it needs to be used
+ * only on memory regions that allows a type (reserved_mem, acpi). For all the
+ * other cases, passing 'MEMBANK_NONE' will disable the exact match.
*/
bool __init check_reserved_regions_overlap(paddr_t region_start,
- paddr_t region_size)
+ paddr_t region_size,
+ enum membank_type allow_match_type)
{
const struct membanks *mem_banks[] = {
bootinfo_get_reserved_mem(),
@@ -190,8 +200,21 @@ bool __init check_reserved_regions_overlap(paddr_t
region_start,
* shared memory banks (when static shared memory feature is enabled)
*/
for ( i = 0; i < ARRAY_SIZE(mem_banks); i++ )
- if ( meminfo_overlap_check(mem_banks[i], region_start, region_size) )
+ {
+ enum membank_type type = allow_match_type;
+
+#ifdef CONFIG_STATIC_SHM
+ /*
+ * Static shared memory banks don't have a type, so for them disable
+ * the exact match check.
+ */
This feels a bit of a hack. Why can't we had a default type like you did
in meminfo_add_bank()?
+ if (mem_banks[i] == bootinfo_get_shmem())
+ type = MEMBANK_NONE;
+#endif
+ if ( meminfo_overlap_check(mem_banks[i], region_start, region_size,
+ type) )
return true;
+ }
/* Check if input region is overlapping with bootmodules */
if ( bootmodules_overlap_check(&bootinfo.modules,
@@ -216,7 +239,12 @@ struct bootmodule __init *add_boot_module(bootmodule_kind
kind,
return NULL;
}
- if ( check_reserved_regions_overlap(start, size) )
+ /*
+ * u-boot adds boot module such as ramdisk to the /memreserve/, since these
+ * ranges are saved in reserved_mem at this stage, allow an eventual exact
+ * match with MEMBANK_FDT_RESVMEM banks.
+ */
+ if ( check_reserved_regions_overlap(start, size, MEMBANK_FDT_RESVMEM) )
return NULL;
for ( i = 0 ; i < mods->nr_mods ; i++ )
diff --git a/xen/include/xen/bootfdt.h b/xen/include/xen/bootfdt.h
index 16fa05f38f38..8f8a7ad882a4 100644
--- a/xen/include/xen/bootfdt.h
+++ b/xen/include/xen/bootfdt.h
@@ -23,6 +23,12 @@ typedef enum {
} bootmodule_kind;
enum membank_type {
+ /*
+ * The MEMBANK_NONE type is a special placeholder that should not be
applied
+ * to a memory bank, it is used as a special value in some function in
order
+ * to disable some feature.
+ */
+ MEMBANK_NONE = -1,
/*
* The MEMBANK_DEFAULT type refers to either reserved memory for the
* device/firmware (when the bank is in 'reserved_mem') or any RAM (when
@@ -158,7 +164,8 @@ struct bootinfo {
extern struct bootinfo bootinfo;
bool check_reserved_regions_overlap(paddr_t region_start,
- paddr_t region_size);
+ paddr_t region_size,
+ enum membank_type allow_match_type);
struct bootmodule *add_boot_module(bootmodule_kind kind,
paddr_t start, paddr_t size, bool domU);
Cheers,
--
Julien Grall
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