This is a note to let you know that I've just added the patch titled
KVM: arm64: Limit stage2_apply_range() batch size to largest block
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-arm64-limit-stage2_apply_range-batch-size-to-largest-block.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 5994bc9e05c2f8811f233aa434e391cd2783f0f5 Mon Sep 17 00:00:00 2001
From: Oliver Upton <oliver.upton@xxxxxxxxx>
Date: Fri, 7 Oct 2022 23:41:51 +0000
Subject: KVM: arm64: Limit stage2_apply_range() batch size to largest block
From: Oliver Upton <oliver.upton@xxxxxxxxx>
commit 5994bc9e05c2f8811f233aa434e391cd2783f0f5 upstream.
Presently stage2_apply_range() works on a batch of memory addressed by a
stage 2 root table entry for the VM. Depending on the IPA limit of the
VM and PAGE_SIZE of the host, this could address a massive range of
memory. Some examples:
4 level, 4K paging -> 512 GB batch size
3 level, 64K paging -> 4TB batch size
Unsurprisingly, working on such a large range of memory can lead to soft
lockups. When running dirty_log_perf_test:
./dirty_log_perf_test -m -2 -s anonymous_thp -b 4G -v 48
watchdog: BUG: soft lockup - CPU#0 stuck for 45s! [dirty_log_perf_:16703]
Modules linked in: vfat fat cdc_ether usbnet mii xhci_pci xhci_hcd sha3_generic gq(O)
CPU: 0 PID: 16703 Comm: dirty_log_perf_ Tainted: G O 6.0.0-smp-DEV #1
pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : dcache_clean_inval_poc+0x24/0x38
lr : clean_dcache_guest_page+0x28/0x4c
sp : ffff800021763990
pmr_save: 000000e0
x29: ffff800021763990 x28: 0000000000000005 x27: 0000000000000de0
x26: 0000000000000001 x25: 00400830b13bc77f x24: ffffad4f91ead9c0
x23: 0000000000000000 x22: ffff8000082ad9c8 x21: 0000fffafa7bc000
x20: ffffad4f9066ce50 x19: 0000000000000003 x18: ffffad4f92402000
x17: 000000000000011b x16: 000000000000011b x15: 0000000000000124
x14: ffff07ff8301d280 x13: 0000000000000000 x12: 00000000ffffffff
x11: 0000000000010001 x10: fffffc0000000000 x9 : ffffad4f9069e580
x8 : 000000000000000c x7 : 0000000000000000 x6 : 000000000000003f
x5 : ffff07ffa2076980 x4 : 0000000000000001 x3 : 000000000000003f
x2 : 0000000000000040 x1 : ffff0830313bd000 x0 : ffff0830313bcc40
Call trace:
dcache_clean_inval_poc+0x24/0x38
stage2_unmap_walker+0x138/0x1ec
__kvm_pgtable_walk+0x130/0x1d4
__kvm_pgtable_walk+0x170/0x1d4
__kvm_pgtable_walk+0x170/0x1d4
__kvm_pgtable_walk+0x170/0x1d4
kvm_pgtable_stage2_unmap+0xc4/0xf8
kvm_arch_flush_shadow_memslot+0xa4/0x10c
kvm_set_memslot+0xb8/0x454
__kvm_set_memory_region+0x194/0x244
kvm_vm_ioctl_set_memory_region+0x58/0x7c
kvm_vm_ioctl+0x49c/0x560
__arm64_sys_ioctl+0x9c/0xd4
invoke_syscall+0x4c/0x124
el0_svc_common+0xc8/0x194
do_el0_svc+0x38/0xc0
el0_svc+0x2c/0xa4
el0t_64_sync_handler+0x84/0xf0
el0t_64_sync+0x1a0/0x1a4
Use the largest supported block mapping for the configured page size as
the batch granularity. In so doing the walker is guaranteed to visit a
leaf only once.
Signed-off-by: Oliver Upton <oliver.upton@xxxxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20221007234151.461779-3-oliver.upton@xxxxxxxxx
Signed-off-by: Krister Johansen <kjlx@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/include/asm/stage2_pgtable.h | 20 --------------------
arch/arm64/kvm/mmu.c | 9 ++++++++-
2 files changed, 8 insertions(+), 21 deletions(-)
--- a/arch/arm64/include/asm/stage2_pgtable.h
+++ b/arch/arm64/include/asm/stage2_pgtable.h
@@ -11,13 +11,6 @@
#include <linux/pgtable.h>
/*
- * PGDIR_SHIFT determines the size a top-level page table entry can map
- * and depends on the number of levels in the page table. Compute the
- * PGDIR_SHIFT for a given number of levels.
- */
-#define pt_levels_pgdir_shift(lvls) ARM64_HW_PGTABLE_LEVEL_SHIFT(4 - (lvls))
-
-/*
* The hardware supports concatenation of up to 16 tables at stage2 entry
* level and we use the feature whenever possible, which means we resolve 4
* additional bits of address at the entry level.
@@ -30,11 +23,6 @@
#define stage2_pgtable_levels(ipa) ARM64_HW_PGTABLE_LEVELS((ipa) - 4)
#define kvm_stage2_levels(kvm) VTCR_EL2_LVLS(kvm->arch.vtcr)
-/* stage2_pgdir_shift() is the size mapped by top-level stage2 entry for the VM */
-#define stage2_pgdir_shift(kvm) pt_levels_pgdir_shift(kvm_stage2_levels(kvm))
-#define stage2_pgdir_size(kvm) (1ULL << stage2_pgdir_shift(kvm))
-#define stage2_pgdir_mask(kvm) ~(stage2_pgdir_size(kvm) - 1)
-
/*
* kvm_mmmu_cache_min_pages() is the number of pages required to install
* a stage-2 translation. We pre-allocate the entry level page table at
@@ -42,12 +30,4 @@
*/
#define kvm_mmu_cache_min_pages(kvm) (kvm_stage2_levels(kvm) - 1)
-static inline phys_addr_t
-stage2_pgd_addr_end(struct kvm *kvm, phys_addr_t addr, phys_addr_t end)
-{
- phys_addr_t boundary = (addr + stage2_pgdir_size(kvm)) & stage2_pgdir_mask(kvm);
-
- return (boundary - 1 < end - 1) ? boundary : end;
-}
-
#endif /* __ARM64_S2_PGTABLE_H_ */
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -31,6 +31,13 @@ static phys_addr_t hyp_idmap_vector;
static unsigned long io_map_base;
+static phys_addr_t stage2_range_addr_end(phys_addr_t addr, phys_addr_t end)
+{
+ phys_addr_t size = kvm_granule_size(KVM_PGTABLE_MIN_BLOCK_LEVEL);
+ phys_addr_t boundary = ALIGN_DOWN(addr + size, size);
+
+ return (boundary - 1 < end - 1) ? boundary : end;
+}
/*
* Release kvm_mmu_lock periodically if the memory region is large. Otherwise,
@@ -52,7 +59,7 @@ static int stage2_apply_range(struct kvm
if (!pgt)
return -EINVAL;
- next = stage2_pgd_addr_end(kvm, addr, end);
+ next = stage2_range_addr_end(addr, end);
ret = fn(pgt, addr, next - addr);
if (ret)
break;
Patches currently in stable-queue which might be from oliver.upton@xxxxxxxxx are
queue-5.15/kvm-arm64-work-out-supported-block-level-at-compile-time.patch
queue-5.15/kvm-arm64-limit-stage2_apply_range-batch-size-to-largest-block.patch
