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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [RFC PATCH] device-tree: size first hwdom bank for boot modules
From: Mykola Kvach <mykola_kvach@xxxxxxxx>
With LLC coloring enabled, the hardware domain memory comes from
allocate_hwdom_memory(), not from the fixed direct-map banks used when
coloring is off.
Commit de99f3263555 ("device-tree: Improve hwdom memory allocation for
DMA") made that allocator sort free host regions by ascending address so
Dom0 gets DMA-capable low memory first. The first bank filter still only
required 128MB. That can select a low region which is large enough for
the heuristic, but not large enough for place_modules() to put the Dom0
kernel, generated DTB and initrd contiguously in bank 0.
Ask arch code for any additional first-bank size requirement. On Arm,
compute it from the actual Dom0 kernel placement, rounded initrd size and
generated DTB size hint. For 64-bit Image kernels, include the text offset
from the candidate bank start, because the returned requirement is compared
with a bank size measured from that start. The hint covers both the normal
Device Tree path and the minimal DTB created for ACPI boot.
Check the first-bank threshold against the size which will actually be
assigned to Dom0, after capping the host region by the remaining unassigned
Dom0 memory. Otherwise a large host region could pass the test but still
produce a first guest bank too small for place_modules().
Use the typed min()/max() helpers for this normal allocation arithmetic;
MIN()/MAX() are intended for preprocessor-style contexts and skip the type
checking provided by the lowercase helpers.
This keeps the DMA-oriented allocation policy from de99f3263555 while
preventing a too-small bank 0 from reaching place_modules().
Fixes: de99f3263555 ("device-tree: Improve hwdom memory allocation for DMA")
Signed-off-by: Mykola Kvach <mykola_kvach@xxxxxxxx>
---
Test/setup notes:
The failure was reproduced on a Renesas H3ULCB/R-Car H3 (r8a7795)
arm64 board booted through U-Boot/TFTP and using huge initrd.
Relevant Xen command line excerpt:
dom0_mem=2048M llc-coloring=on
Boot module layout from Xen:
MODULE[2]: 0x0000000084000040-0x000000008e75d92f Ramdisk
MODULE[3]: 0x00000000a0000000-0x00000000a3ffffff Kernel
MODULE[4]: 0x00000000a4000000-0x00000000a400ffff XSM Policy
The initrd is about 168MB. With LLC coloring enabled and the low-address
allocation policy from de99f3263555, Dom0 can receive a 192MB first bank:
d0 BANK[0] 0x00000048000000-0x00000054000000 (192MB)
That bank satisfies the old 128MB minimum but is too small for the
rounded Dom0 kernel, generated DTB and initrd placement. The observed
failure before this patch was:
Panic on CPU 0:
Not enough memory in the first bank for the kernel+dtb+initrd
With this patch, the same boot skips the too-small low region for bank 0
and reaches Dom0:
d0 BANK[0] 0x00000057000000-0x00000084000000 (720MB)
d0 BANK[1] 0x0000008e800000-0x000000c0000000 (792MB)
d0 BANK[2] 0x00000500000000-0x00000521800000 (536MB)
d0: extended region 0: 0x48000000->0x54000000
Loading zImage from 0x00000000a0000000 to 0x57000000-0x5b000000
Loading d0 initrd from 0x0000000084000040 to 0x5f200000-0x6995d8f0
Loading d0 DTB to 0x5f000000-0x5f011c80
Linux version 5.10.194-yocto-standard
---
xen/arch/arm/acpi/domain_build.c | 2 --
xen/arch/arm/domain_build.c | 8 ++++++
xen/arch/arm/include/asm/domain_build.h | 4 +++
xen/arch/arm/include/asm/kernel.h | 8 ++++++
xen/arch/arm/kernel.c | 35 +++++++++++++++++++++++++
xen/common/device-tree/domain-build.c | 27 ++++++++++++++-----
xen/include/xen/fdt-kernel.h | 8 ++++++
7 files changed, 83 insertions(+), 9 deletions(-)
diff --git a/xen/arch/arm/acpi/domain_build.c b/xen/arch/arm/acpi/domain_build.c
index 249d899c33..db16f7fa94 100644
--- a/xen/arch/arm/acpi/domain_build.c
+++ b/xen/arch/arm/acpi/domain_build.c
@@ -26,8 +26,6 @@
#undef virt_to_mfn
#define virt_to_mfn(va) _mfn(__virt_to_mfn(va))
-#define ACPI_DOM0_FDT_MIN_SIZE 4096
-
static int __init acpi_iomem_deny_access(struct domain *d)
{
acpi_status status;
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 1efddc60ef..226e053c68 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -115,6 +115,14 @@ int __init parse_arch_dom0_param(const char *s, const char
*e)
(IS_ENABLED(CONFIG_STATIC_SHM) ? \
(NR_SHMEM_BANKS * (160 + 16)) : 0))
+paddr_t __init dom0_get_fdt_size_hint(void)
+{
+ if ( !acpi_disabled )
+ return ACPI_DOM0_FDT_MIN_SIZE;
+
+ return fdt_totalsize(device_tree_flattened) + DOM0_FDT_EXTRA_SIZE;
+}
+
unsigned int __init dom0_max_vcpus(void)
{
if ( opt_dom0_max_vcpus == 0 )
diff --git a/xen/arch/arm/include/asm/domain_build.h
b/xen/arch/arm/include/asm/domain_build.h
index df8b361b3d..45687c5d6f 100644
--- a/xen/arch/arm/include/asm/domain_build.h
+++ b/xen/arch/arm/include/asm/domain_build.h
@@ -19,6 +19,10 @@ int prepare_acpi(struct domain *d, struct kernel_info
*kinfo);
int add_ext_regions(unsigned long s_gfn, unsigned long e_gfn, void *data);
+#define ACPI_DOM0_FDT_MIN_SIZE 4096
+
+paddr_t dom0_get_fdt_size_hint(void);
+
#if defined(CONFIG_MPU) && defined(CONFIG_ARM_64)
/* Utility function to determine if an Armv8-R processor supports VMSA. */
bool has_v8r_vmsa_support(void);
diff --git a/xen/arch/arm/include/asm/kernel.h
b/xen/arch/arm/include/asm/kernel.h
index 21f4273fa1..17c5b9bce4 100644
--- a/xen/arch/arm/include/asm/kernel.h
+++ b/xen/arch/arm/include/asm/kernel.h
@@ -8,12 +8,20 @@
#include <asm/domain.h>
+#include <xen/types.h>
+
+struct kernel_info;
+
struct arch_kernel_info
{
/* Enable pl011 emulation */
bool vpl011;
};
+#define arch_get_min_first_bank_size arch_get_min_first_bank_size
+paddr_t arch_get_min_first_bank_size(struct kernel_info *info,
+ paddr_t bank_start);
+
#endif /* #ifdef __ARCH_ARM_KERNEL_H__ */
/*
diff --git a/xen/arch/arm/kernel.c b/xen/arch/arm/kernel.c
index b72585b7fe..3644663e2f 100644
--- a/xen/arch/arm/kernel.c
+++ b/xen/arch/arm/kernel.c
@@ -128,6 +128,41 @@ static paddr_t __init kernel_zimage_place(struct
kernel_info *info)
return load_addr;
}
+static paddr_t __init kernel_placement_size(paddr_t load_addr, paddr_t len)
+{
+ return ROUNDUP(load_addr + len, MB(2)) - load_addr;
+}
+
+paddr_t __init arch_get_min_first_bank_size(struct kernel_info *info,
+ paddr_t bank_start)
+{
+ const struct boot_module *mod = info->bd.initrd;
+ const paddr_t initrd_len = ROUNDUP(mod ? mod->size : 0, MB(2));
+ const paddr_t dtb_len = ROUNDUP(dom0_get_fdt_size_hint(), MB(2));
+ paddr_t kernsize;
+
+#ifdef CONFIG_HAS_DOMAIN_TYPE
+ if ( (info->type == DOMAIN_64BIT) && (info->image.start == 0) )
+ {
+ paddr_t load_addr = bank_start + info->image.text_offset;
+
+ /*
+ * The caller compares this value with a size measured from
+ * bank_start, so include the text offset before the kernel.
+ */
+ kernsize = ROUNDUP(load_addr + info->image.len, MB(2)) - bank_start;
+ return kernsize + initrd_len + dtb_len;
+ }
+#endif
+
+ if ( info->image.start == 0 )
+ kernsize = ROUNDUP(info->image.len, MB(2));
+ else
+ kernsize = kernel_placement_size(info->image.start, info->image.len);
+
+ return kernsize + initrd_len + dtb_len;
+}
+
static void __init kernel_zimage_load(struct kernel_info *info)
{
paddr_t load_addr = kernel_zimage_place(info);
diff --git a/xen/common/device-tree/domain-build.c
b/xen/common/device-tree/domain-build.c
index 2a760b007b..d8865db259 100644
--- a/xen/common/device-tree/domain-build.c
+++ b/xen/common/device-tree/domain-build.c
@@ -299,20 +299,33 @@ static bool __init allocate_hwdom_memory(struct
kernel_info *kinfo)
for ( i = 0; (kinfo->unassigned_mem > 0) && (i < nr_banks); i++ )
{
- paddr_t bank_size;
+ const paddr_t bank_start = hwdom_free_mem->bank[i].start;
+ paddr_t bank_size = hwdom_free_mem->bank[i].size;
+
+ /*
+ * Check the size that would actually be assigned, not just the size
+ * of the host region.
+ */
+ bank_size = min(bank_size, kinfo->unassigned_mem);
/*
* The first bank must be large enough for place_modules() to
* fit the kernel, DTB and initrd. Skip small regions to avoid
* ending up with a tiny first bank.
*/
- if ( !mem->nr_banks && (hwdom_free_mem->bank[i].size < min_bank_size) )
- continue;
+ if ( !mem->nr_banks )
+ {
+ paddr_t arch_min_size;
+ paddr_t required_first_bank_size;
+
+ arch_min_size = arch_get_min_first_bank_size(kinfo, bank_start);
+ required_first_bank_size = max(min_bank_size, arch_min_size);
+
+ if ( bank_size < required_first_bank_size )
+ continue;
+ }
- bank_size = MIN(hwdom_free_mem->bank[i].size, kinfo->unassigned_mem);
- if ( !allocate_bank_memory(kinfo,
- gaddr_to_gfn(hwdom_free_mem->bank[i].start),
- bank_size) )
+ if ( !allocate_bank_memory(kinfo, gaddr_to_gfn(bank_start), bank_size)
)
{
xfree(hwdom_free_mem);
return false;
diff --git a/xen/include/xen/fdt-kernel.h b/xen/include/xen/fdt-kernel.h
index 8cd1670c2c..931b3e1686 100644
--- a/xen/include/xen/fdt-kernel.h
+++ b/xen/include/xen/fdt-kernel.h
@@ -86,6 +86,14 @@ kernel_info_get_mem_const(const struct kernel_info *kinfo)
return container_of(&kinfo->mem.common, const struct membanks, common);
}
+#ifndef arch_get_min_first_bank_size
+static inline paddr_t arch_get_min_first_bank_size(struct kernel_info *info,
+ paddr_t bank_start)
+{
+ return 0;
+}
+#endif
+
#ifndef KERNEL_INFO_SHM_MEM_INIT
#ifdef CONFIG_STATIC_SHM
--
2.43.0
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