Re: [PATCH v6 00/10] KVM: selftests: some improvement and a new test for kvm page table
From: Paolo Bonzini
Date: Sat Apr 17 2021 - 09:23:01 EST
On 06/04/21 05:05, wangyanan (Y) wrote:
Kindly ping...
Hi Paolo,
Will this series be picked up soon, or is there any other work for me to
do?
Regards,
Yanan
On 2021/3/30 16:08, Yanan Wang wrote:
Hi,
This v6 series can mainly include two parts.
Rebased on kvm queue branch:
https://git.kernel.org/pub/scm/virt/kvm/kvm.git/log/?h=queue
In the first part, all the known hugetlb backing src types specified
with different hugepage sizes are listed, so that we can specify use
of hugetlb source of the exact granularity that we want, instead of
the system default ones. And as all the known hugetlb page sizes are
listed, it's appropriate for all architectures. Besides, a helper that
can get granularity of different backing src types(anonumous/thp/hugetlb)
is added, so that we can use the accurate backing src granularity for
kinds of alignment or guest memory accessing of vcpus.
In the second part, a new test is added:
This test is added to serve as a performance tester and a bug reproducer
for kvm page table code (GPA->HPA mappings), it gives guidance for the
people trying to make some improvement for kvm. And the following
explains
what we can exactly do through this test.
The function guest_code() can cover the conditions where a single vcpu or
multiple vcpus access guest pages within the same memory region, in three
VM stages(before dirty logging, during dirty logging, after dirty
logging).
Besides, the backing src memory type(ANONYMOUS/THP/HUGETLB) of the tested
memory region can be specified by users, which means normal page mappings
or block mappings can be chosen by users to be created in the test.
If ANONYMOUS memory is specified, kvm will create normal page mappings
for the tested memory region before dirty logging, and update attributes
of the page mappings from RO to RW during dirty logging. If THP/HUGETLB
memory is specified, kvm will create block mappings for the tested memory
region before dirty logging, and split the blcok mappings into normal
page
mappings during dirty logging, and coalesce the page mappings back into
block mappings after dirty logging is stopped.
So in summary, as a performance tester, this test can present the
performance of kvm creating/updating normal page mappings, or the
performance of kvm creating/splitting/recovering block mappings,
through execution time.
When we need to coalesce the page mappings back to block mappings after
dirty logging is stopped, we have to firstly invalidate *all* the TLB
entries for the page mappings right before installation of the block
entry,
because a TLB conflict abort error could occur if we can't invalidate the
TLB entries fully. We have hit this TLB conflict twice on aarch64
software
implementation and fixed it. As this test can imulate process from dirty
logging enabled to dirty logging stopped of a VM with block mappings,
so it can also reproduce this TLB conflict abort due to inadequate TLB
invalidation when coalescing tables.
Links about the TLB conflict abort:
https://lore.kernel.org/lkml/20201201201034.116760-3-wangyanan55@xxxxxxxxxx/
---
Change logs:
v5->v6:
- Address Andrew Jones's comments for v5 series
- Add Andrew Jones's R-b tags in some patches
- Rebased on newest kvm/queue tree
- v5:
https://lore.kernel.org/lkml/20210323135231.24948-1-wangyanan55@xxxxxxxxxx/
v4->v5:
- Use synchronization(sem_wait) for time measurement
- Add a new patch about TEST_ASSERT(patch 4)
- Address Andrew Jones's comments for v4 series
- Add Andrew Jones's R-b tags in some patches
- v4:
https://lore.kernel.org/lkml/20210302125751.19080-1-wangyanan55@xxxxxxxxxx/
v3->v4:
- Add a helper to get system default hugetlb page size
- Add tags of Reviewed-by of Ben in the patches
- v3:
https://lore.kernel.org/lkml/20210301065916.11484-1-wangyanan55@xxxxxxxxxx/
v2->v3:
- Add tags of Suggested-by, Reviewed-by in the patches
- Add a generic micro to get hugetlb page sizes
- Some changes for suggestions about v2 series
- v2:
https://lore.kernel.org/lkml/20210225055940.18748-1-wangyanan55@xxxxxxxxxx/
v1->v2:
- Add a patch to sync header files
- Add helpers to get granularity of different backing src types
- Some changes for suggestions about v1 series
- v1:
https://lore.kernel.org/lkml/20210208090841.333724-1-wangyanan55@xxxxxxxxxx/
---
Yanan Wang (10):
tools headers: sync headers of asm-generic/hugetlb_encode.h
mm/hugetlb: Add a macro to get HUGETLB page sizes for mmap
KVM: selftests: Use flag CLOCK_MONOTONIC_RAW for timing
KVM: selftests: Print the errno besides error-string in TEST_ASSERT
KVM: selftests: Make a generic helper to get vm guest mode strings
KVM: selftests: Add a helper to get system configured THP page size
KVM: selftests: Add a helper to get system default hugetlb page size
KVM: selftests: List all hugetlb src types specified with page sizes
KVM: selftests: Adapt vm_userspace_mem_region_add to new helpers
KVM: selftests: Add a test for kvm page table code
include/uapi/linux/mman.h | 2 +
tools/include/asm-generic/hugetlb_encode.h | 3 +
tools/include/uapi/linux/mman.h | 2 +
tools/testing/selftests/kvm/.gitignore | 1 +
tools/testing/selftests/kvm/Makefile | 3 +
.../selftests/kvm/demand_paging_test.c | 8 +-
.../selftests/kvm/dirty_log_perf_test.c | 14 +-
.../testing/selftests/kvm/include/kvm_util.h | 4 +-
.../testing/selftests/kvm/include/test_util.h | 21 +-
.../selftests/kvm/kvm_page_table_test.c | 506 ++++++++++++++++++
tools/testing/selftests/kvm/lib/assert.c | 4 +-
tools/testing/selftests/kvm/lib/kvm_util.c | 59 +-
tools/testing/selftests/kvm/lib/test_util.c | 163 +++++-
tools/testing/selftests/kvm/steal_time.c | 4 +-
14 files changed, 733 insertions(+), 61 deletions(-)
create mode 100644 tools/testing/selftests/kvm/kvm_page_table_test.c
Queued, thanks.
I moved MAP_HUGE_PAGE_SIZE from the uapi header to test_util.c, because
I'm not confident in adding a new userspace API without an ack.
Paolo