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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 On 7/27/26 21:58, Yosry Ahmed wrote: > On Mon, Jul 27, 2026 at 12:23 PM Tycho Andersen wrote: >> >> Hi all, >> >> On Thu, Jul 23, 2026 at 11:44:19AM +0200, Paolo Bonzini wrote: >>> As to the workload, Alexander threw more or less everything at the same >>> time at the VM: >>> >>> - a full Windows Defender scan every 30 minutes >>> >>> - a disk I/O job >>> >>> - a loop doing repeated mmap of system files (mostly to hope that >>> it triggers some consistency check in the Windows memory manager) >>> >>> - SQL Express 2022 + StressDB (1.6M rows), with the host doing queries >>> (75% write/25% read) via sqlcmd >> >> Can you share the code for the mmap + disk io + DB content generator? >> >> We're looking at this and would like to reproduce. > > Not sure if this is relevant, but I see that hyperv_tlb_flush is flaky > with npt=0 on Turin at the tip of kvm-x86/next (commit 567329869b9c7). Same on Milan, but ept=0 works. > It's not likely because the problem fixed by this patch happens > specifically with npt=1 and not npt=0 AFAICT, but it is a weird > coincidence :) And also because this patch uses, in the end, the same flush mechanism that npt=0 and ept=0 already use. So that bug is probably in npt=0. That said, I'll do a quick experiment of running hyperv_tlb_flush in a loop with this patch. Paolo > Maybe something is wrong in the Hyper-V code that manifests > differently with npt=0/1?