Hi Will,
On 9/3/20 10:16 PM, Will Deacon wrote:
On Thu, Sep 03, 2020 at 09:48:18PM +1000, Gavin Shan wrote:
On 9/3/20 9:13 PM, Gavin Shan wrote:
On 9/3/20 5:34 PM, Gavin Shan wrote:
On 8/25/20 7:39 PM, Will Deacon wrote:
Hello folks,
This is version three of the KVM page-table rework that I previously posted
here:
v1: https://lore.kernel.org/r/20200730153406.25136-1-will@xxxxxxxxxx
v2: https://lore.kernel.org/r/20200818132818.16065-1-will@xxxxxxxxxx
Changes since v2 include:
* Rebased onto -rc2, which includes the conflicting OOM blocking fixes
* Dropped the patch trying to "fix" the memcache in kvm_phys_addr_ioremap()
It's really nice work, making the code unified/simplified greatly.
However, it seems it doesn't work well with HugeTLBfs. Please refer
to the following test result and see if you have quick idea, or I
can debug it a bit :)
Nice testing matrix, and thanks for reporting the problem!
Machine Host Guest Result
===============================================================
ThunderX2 VA_BITS: 42 PAGE_SIZE: 4KB Passed
PAGE_SIZE: 64KB 64KB passed
THP: disabled
HugeTLB: disabled
---------------------------------------------------------------
ThunderX2 VA_BITS: 42 PAGE_SIZE: 4KB Passed
PAGE_SIZE: 64KB 64KB passed
THP: enabled
HugeTLB: disabled
----------------------------------------------------------------
ThunderX2 VA_BITS: 42 PAGE_SIZE: 4KB Fail[1]
PAGE_SIZE: 64KB 64KB Fail[1]
THP: disabled
HugeTLB: enabled
---------------------------------------------------------------
ThunderX2 VA_BITS: 39 PAGE_SIZE: 4KB Passed
PAGE_SIZE: 4KB 64KB Passed
THP: disabled
HugeTLB: disabled
---------------------------------------------------------------
ThunderX2 VA_BITS: 39 PAGE_SIZE: 4KB Passed
PAGE_SIZE: 4KB 64KB Passed
THP: enabled
HugeTLB: disabled
--------------------------------------------------------------
ThunderX2 VA_BITS: 39 PAGE_SIZE: 4KB Fail[2]
PAGE_SIZE: 4KB 64KB Fail[2]
THP: disabled
HugeTLB: enabled
I debugged the code and found the issue is caused by the following
patch.
[PATCH v3 06/21] KVM: arm64: Add support for stage-2 map()/unmap() in generic page-table
(I think this is just a symptom of the page-table being out of whack)
Sorry that the guest could hang sometimes with above changes. I have no idea what
has been happening before I'm going to debug for more.. I'm pasting the used command
and output from guest.
Can you try the diff below, please? I think we can end up sticking down a
huge-page-sized mapping at an unaligned address, which causes us both to
overmap and also to fail to use the huge granule for a block mapping.
Since the the following changes have been folded to v4, I reran the test cases
on v4 and everything works fine.
Thanks,
Gavin
--->8
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index f28e03dcb897..3bff942e5f33 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -737,11 +737,11 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
bool exec_fault;
bool device = false;
unsigned long mmu_seq;
- gfn_t gfn = fault_ipa >> PAGE_SHIFT;
struct kvm *kvm = vcpu->kvm;
struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
struct vm_area_struct *vma;
short vma_shift;
+ gfn_t gfn;
kvm_pfn_t pfn;
bool logging_active = memslot_is_logging(memslot);
unsigned long vma_pagesize;
@@ -780,7 +780,9 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
}
if (vma_pagesize == PMD_SIZE || vma_pagesize == PUD_SIZE)
- gfn = (fault_ipa & huge_page_mask(hstate_vma(vma))) >> PAGE_SHIFT;
+ fault_ipa &= huge_page_mask(hstate_vma(vma));
+
+ gfn = fault_ipa >> PAGE_SHIFT;
mmap_read_unlock(current->mm);
if (fault_status != FSC_PERM) {
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