From: Sean Christopherson <seanjc@google.com>
To: "wangyanan (Y)" <wangyanan55@huawei.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Ben Gardon <bgardon@google.com>,
Andrew Jones <drjones@redhat.com>, Peter Xu <peterx@redhat.com>,
Aaron Lewis <aaronlewis@google.com>
Subject: Re: [PATCH 03/15] KVM: selftests: Align HVA for HugeTLB-backed memslots
Date: Fri, 12 Mar 2021 16:17:17 -0800 [thread overview]
Message-ID: <YEwEjQZZJXvNWYna@google.com> (raw)
In-Reply-To: <eac3f8b1-0e5b-395f-7fd7-75409554bffc@huawei.com>
On Thu, Feb 25, 2021, wangyanan (Y) wrote:
> Hi Sean,
>
> On 2021/2/11 7:06, Sean Christopherson wrote:
> > Align the HVA for HugeTLB memslots, not just THP memslots. Add an
> > assert so any future backing types are forced to assess whether or not
> > they need to be aligned.
> >
> > Cc: Ben Gardon <bgardon@google.com>
> > Cc: Yanan Wang <wangyanan55@huawei.com>
> > Cc: Andrew Jones <drjones@redhat.com>
> > Cc: Peter Xu <peterx@redhat.com>
> > Cc: Aaron Lewis <aaronlewis@google.com>
> > Signed-off-by: Sean Christopherson <seanjc@google.com>
> > ---
> > tools/testing/selftests/kvm/lib/kvm_util.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> > index 584167c6dbc7..deaeb47b5a6d 100644
> > --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> > +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> > @@ -731,8 +731,11 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
> > alignment = 1;
> > #endif
> > - if (src_type == VM_MEM_SRC_ANONYMOUS_THP)
> > + if (src_type == VM_MEM_SRC_ANONYMOUS_THP ||
> > + src_type == VM_MEM_SRC_ANONYMOUS_HUGETLB)
> Sorry for the late reply, I just returned from vacation.
At least you had an excuse :-)
> I am not sure HVA alignment is really necessary here for hugetlb pages.
> Different from hugetlb pages, the THP pages are dynamically allocated by
> later madvise(), so the value of HVA returned from mmap() is host page size
> aligned but not THP page size aligned, so we indeed have to perform
> alignment. But hugetlb pages are pre-allocated on systems. The following
> test results also indicate that, with MAP_HUGETLB flag, the HVA returned from
> mmap() is already aligned to the corresponding hugetlb page size. So maybe
> HVAs of each hugetlb pages are aligned during allocation of them or in mmap()?
Yep, I verified the generic and arch version of hugetlb_get_unmapped_area() that
KVM supports all align the address. PARISC64 is the only one that looks suspect,
but it doesn't support KVM.
> If so, I think we better not do this again here, because the later
> *region->mmap_size += alignment* will cause one more hugetlb page mapped but
> will not be used.
Agreed. I think I'll still add the assert, along with a comment calling out
that HugetlB automatically handles alignment.
Nice catch, thanks!
next prev parent reply other threads:[~2021-03-13 0:18 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-10 23:06 [PATCH 00/15] VM: selftests: Hugepage fixes and cleanups Sean Christopherson
2021-02-10 23:06 ` [PATCH 01/15] KVM: selftests: Explicitly state indicies for vm_guest_mode_params array Sean Christopherson
2021-02-11 0:50 ` Ben Gardon
2021-02-10 23:06 ` [PATCH 02/15] KVM: selftests: Expose align() helpers to tests Sean Christopherson
2021-02-11 0:49 ` Ben Gardon
2021-02-10 23:06 ` [PATCH 03/15] KVM: selftests: Align HVA for HugeTLB-backed memslots Sean Christopherson
2021-02-11 0:52 ` Ben Gardon
2021-02-25 7:40 ` wangyanan (Y)
2021-03-13 0:17 ` Sean Christopherson [this message]
2021-02-10 23:06 ` [PATCH 04/15] KVM: selftests: Force stronger HVA alignment (1gb) for hugepages Sean Christopherson
2021-02-25 7:57 ` wangyanan (Y)
2021-03-13 0:26 ` Sean Christopherson
2021-02-10 23:06 ` [PATCH 05/15] KVM: selftests: Require GPA to be aligned when backed by hugepages Sean Christopherson
2021-02-11 1:01 ` Ben Gardon
2021-02-10 23:06 ` [PATCH 06/15] KVM: selftests: Use shorthand local var to access struct perf_tests_args Sean Christopherson
2021-02-11 1:09 ` Ben Gardon
2021-02-10 23:06 ` [PATCH 07/15] KVM: selftests: Capture per-vCPU GPA in perf_test_vcpu_args Sean Christopherson
2021-02-11 1:24 ` Ben Gardon
2021-02-10 23:06 ` [PATCH 08/15] KVM: selftests: Use perf util's per-vCPU GPA/pages in demand paging test Sean Christopherson
2021-02-11 1:23 ` Ben Gardon
2021-02-10 23:06 ` [PATCH 09/15] KVM: selftests: Move per-VM GPA into perf_test_args Sean Christopherson
2021-02-11 1:22 ` Ben Gardon
2021-02-11 1:56 ` Sean Christopherson
2021-02-11 13:12 ` Paolo Bonzini
2021-02-11 15:57 ` Sean Christopherson
2021-02-11 17:33 ` Ben Gardon
2021-02-10 23:06 ` [PATCH 10/15] KVM: selftests: Remove perf_test_args.host_page_size Sean Christopherson
2021-02-11 1:26 ` Ben Gardon
2021-02-10 23:06 ` [PATCH 11/15] KVM: selftests: Create VM with adjusted number of guest pages for perf tests Sean Christopherson
2021-02-11 1:32 ` Ben Gardon
2021-02-10 23:06 ` [PATCH 12/15] KVM: selftests: Fill per-vCPU struct during "perf_test" VM creation Sean Christopherson
2021-02-10 23:06 ` [PATCH 13/15] KVM: selftests: Sync perf_test_args to guest during " Sean Christopherson
2021-02-10 23:06 ` [PATCH 14/15] KVM: selftests: Track size of per-VM memslot in perf_test_args Sean Christopherson
2021-02-10 23:06 ` [PATCH 15/15] KVM: selftests: Get rid of gorilla math in memslots modification test Sean Christopherson
2021-02-11 11:58 ` [PATCH 00/15] VM: selftests: Hugepage fixes and cleanups Andrew Jones
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