From: Ben Gardon <bgardon@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
linux-kselftest@vger.kernel.org,
Cannon Matthews <cannonmatthews@google.com>,
Peter Xu <peterx@redhat.com>, Andrew Jones <drjones@redhat.com>,
Peter Shier <pshier@google.com>, Oliver Upton <oupton@google.com>
Subject: Re: [PATCH v4 09/10] KVM: selftests: Stop memslot creation in KVM internal memslot region
Date: Mon, 27 Jan 2020 09:28:01 -0800 [thread overview]
Message-ID: <CANgfPd81ocW0O4nqSnfBwEn_V-ZzY_WJ=TvymCBfy_w5==GxmQ@mail.gmail.com> (raw)
In-Reply-To: <6812a36c-7de6-c0c9-a2f3-5f9e02db6621@redhat.com>
On Sat, Jan 25, 2020 at 1:37 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 24/01/20 19:41, Ben Gardon wrote:
> > On Fri, Jan 24, 2020 at 12:58 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
> >>
> >> On 23/01/20 19:04, Ben Gardon wrote:
> >>> KVM creates internal memslots covering the region between 3G and 4G in
> >>> the guest physical address space, when the first vCPU is created.
> >>> Mapping this region before creation of the first vCPU causes vCPU
> >>> creation to fail. Prohibit tests from creating such a memslot and fail
> >>> with a helpful warning when they try to.
> >>>
> >>> Signed-off-by: Ben Gardon <bgardon@google.com>
> >>> ---
> >>
> >> The internal memslots are much higher than this (0xfffbc000 and
> >> 0xfee00000). I'm changing the patch to block 0xfe0000000 and above,
> >> otherwise it breaks vmx_dirty_log_test.
> >
> > Perhaps we're working in different units, but I believe paddrs
> > 0xfffbc000 and 0xfee00000 are between 3GiB and 4GiB.
> > "Proof by Python":
>
> I invoke the "not a native speaker" card. Rephrasing: there is a large
> part at the beginning of the area between 3GiB and 4GiB that isn't used
> by internal memslot (but is used by vmx_dirty_log_test).
Ah, that makes perfect sense, thank you for clarifying. I think the
3G-4G in my head may have come from the x86 PCI hole or similar. In
any case, reducing the prohibited range to just the range covered by
internal memslots feels like a good change.
> Though I have no excuse for the extra zero, the range to block is
> 0xfe000000 to 0x100000000.
>
> Paolo
>
> >>>> B=1
> >>>> KB=1024*B
> >>>> MB=1024*KB
> >>>> GB=1024*MB
> >>>> hex(3*GB)
> > '0xc0000000'
> >>>> hex(4*GB)
> > '0x100000000'
> >>>> 3*GB == 3<<30
> > True
> >>>> 0xfffbc000 > 3*GB
> > True
> >>>> 0xfffbc000 < 4*GB
> > True
> >>>> 0xfee00000 > 3*GB
> > True
> >>>> 0xfee00000 < 4*GB
> > True
> >
> > Am I missing something?
> >
> > I don't think blocking 0xfe0000000 and above is useful, as there's
> > nothing mapped in that region and AFAIK it's perfectly valid to create
> > memslots there.
> >
> >
> >>
> >> Paolo
> >>
> >
>
next prev parent reply other threads:[~2020-01-27 17:28 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-23 18:04 [PATCH v4 00/10] Create a userfaultfd demand paging test Ben Gardon
2020-01-23 18:04 ` [PATCH v4 01/10] KVM: selftests: Create a " Ben Gardon
2020-01-24 9:49 ` Andrew Jones
2020-01-27 9:18 ` Thomas Huth
2020-01-23 18:04 ` [PATCH v4 02/10] KVM: selftests: Add demand paging content to the " Ben Gardon
2020-01-23 18:04 ` [PATCH v4 03/10] KVM: selftests: Add configurable demand paging delay Ben Gardon
2020-01-23 18:04 ` [PATCH v4 04/10] KVM: selftests: Add memory size parameter to the demand paging test Ben Gardon
2020-01-24 10:01 ` Andrew Jones
2020-01-23 18:04 ` [PATCH v4 05/10] KVM: selftests: Pass args to vCPU in global vCPU args struct Ben Gardon
2020-01-23 18:04 ` [PATCH v4 06/10] KVM: selftests: Add support for vcpu_args_set to aarch64 and s390x Ben Gardon
2020-01-24 9:03 ` Paolo Bonzini
2020-01-24 9:35 ` Andrew Jones
2020-01-24 9:44 ` Paolo Bonzini
2020-01-24 10:45 ` Andrew Jones
2020-01-24 18:33 ` Christian Borntraeger
2020-01-25 9:34 ` Paolo Bonzini
2020-01-27 8:38 ` Andrew Jones
2020-01-27 9:01 ` Thomas Huth
2020-01-23 18:04 ` [PATCH v4 07/10] KVM: selftests: Support multiple vCPUs in demand paging test Ben Gardon
2020-01-24 10:16 ` Andrew Jones
2020-01-24 10:49 ` Andrew Jones
2020-01-25 9:39 ` Paolo Bonzini
2020-01-27 8:39 ` Andrew Jones
2020-01-23 18:04 ` [PATCH v4 08/10] KVM: selftests: Time guest demand paging Ben Gardon
2020-01-24 10:21 ` Andrew Jones
2020-01-23 18:04 ` [PATCH v4 09/10] KVM: selftests: Stop memslot creation in KVM internal memslot region Ben Gardon
2020-01-24 8:58 ` Paolo Bonzini
2020-01-24 18:41 ` Ben Gardon
2020-01-25 9:37 ` Paolo Bonzini
2020-01-27 17:28 ` Ben Gardon [this message]
2020-01-23 18:04 ` [PATCH v4 10/10] KVM: selftests: Move memslot 0 above KVM internal memslots Ben Gardon
2020-01-24 9:01 ` Paolo Bonzini
2020-01-24 18:53 ` Ben Gardon
2020-01-27 9:42 ` Thomas Huth
2020-01-24 9:03 ` [PATCH v4 00/10] Create a userfaultfd demand paging test Paolo Bonzini
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