Hi Drew,
On 8/19/22 3:28 PM, Andrew Jones wrote:
On Fri, Aug 19, 2022 at 08:55:59AM +0800, Gavin Shan wrote:
It's assumed that 1024 host pages, instead of guest pages, are dirtied
in each iteration in guest_code(). The current implementation misses
the case of mismatched page sizes in host and guest. For example,
ARM64 could have 64KB page size in guest, but 4KB page size in host.
(TEST_PAGES_PER_LOOP / 16), instead of TEST_PAGES_PER_LOOP, host pages
are dirtied in every iteration.
Fix the issue by touching all sub-pages when we have mismatched
page sizes in host and guest.
I'll let the dirty-log test authors decide what's best to do for this
test, but I'd think we should let the guest continue dirtying its
pages without knowledge of the host pages. Then, adjust the host test
code to assert all sub-pages, other than the ones it expects the guest
to have written, remain untouched.
I don't think what is clarified in the change log is correct. The current
implementation already had the logic to handle the mismatched page sizes
in vm_dirty_log_verify() where 'step' is used for it by fetching value
from vm_num_host_pages(mode, 1). Please ignore this patch for now, as
explained below.
The issue I have is the 'dirty_log_test' hangs when I have 4KB host page size
and 64KB guest page size. It seems the vcpu doesn't exit due to full ring
buffer state or kick-off. I will have more investigations to figure out the
root cause.
# ./dirty_log_test -M dirty-ring -m 7
Setting log mode to: 'dirty-ring'
Test iterations: 32, interval: 10 (ms)
Testing guest mode: PA-bits:40, VA-bits:48, 64K pages
guest physical test memory offset: 0xffbffc0000
vcpu stops because vcpu is kicked out...
Notifying vcpu to continue
vcpu continues now.
Iteration 1 collected 1903 pages
<no more output>
'dirty_lot_test' works well when both host and guest have 4KB page size.
# ./dirty_log_test -M dirty-ring -m 5
Setting log mode to: 'dirty-ring'
Test iterations: 32, interval: 10 (ms)
Testing guest mode: PA-bits:40, VA-bits:48, 4K pages
guest physical test memory offset: 0xffbfffc000
vcpu stops because vcpu is kicked out...
Notifying vcpu to continue
vcpu continues now.
:
Dirtied 1006592 pages
Total bits checked: dirty (1020487), clear (7106070), track_next (974104)
Thanks,
Gavin
