From: Sean Christopherson <seanjc@google.com>
To: Andrzej Hajda <andrzej.hajda@intel.com>
Cc: Wei Wang <wei.w.wang@intel.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Zhenyu Wang <zhenyuw@linux.intel.com>,
Zhi Wang <zhi.a.wang@intel.com>, Yan Zhao <yan.y.zhao@intel.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"intel-gfx@lists.freedesktop.org"
<intel-gfx@lists.freedesktop.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Ben Gardon <bgardon@google.com>,
"intel-gvt-dev@lists.freedesktop.org"
<intel-gvt-dev@lists.freedesktop.org>
Subject: Re: [Intel-gfx] [PATCH v2 01/27] drm/i915/gvt: Verify pfn is "valid" before dereferencing "struct page"
Date: Wed, 15 Mar 2023 12:23:20 -0700 [thread overview]
Message-ID: <ZBIQ1vxLs10UFi3R@google.com> (raw)
In-Reply-To: <871f7c8b-0f54-7e9c-4253-b3878b010bbf@intel.com>
On Wed, Mar 15, 2023, Andrzej Hajda wrote:
> On 13.03.2023 16:37, Wang, Wei W wrote:
> > On Saturday, March 11, 2023 8:23 AM, Sean Christopherson wrote:
> > > diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
> > > index 4ec85308379a..58b9b316ae46 100644
> > > --- a/drivers/gpu/drm/i915/gvt/gtt.c
> > > +++ b/drivers/gpu/drm/i915/gvt/gtt.c
> > > @@ -1183,6 +1183,10 @@ static int is_2MB_gtt_possible(struct intel_vgpu
> > > *vgpu,
> > > pfn = gfn_to_pfn(vgpu->vfio_device.kvm, ops->get_pfn(entry));
> > > if (is_error_noslot_pfn(pfn))
> > > return -EINVAL;
> > > +
> > > + if (!pfn_valid(pfn))
> > > + return -EINVAL;
> > > +
> >
> > Merge the two errors in one "if" to have less LOC?
> > i.e.
> > if (is_error_noslot_pfn(pfn) || !pfn_valid(pfn))
> > return -EINVAL;
>
> you can just replace "if (is_error_noslot_pfn(pfn))" with "if
> (!pfn_valid(pfn))", it covers both cases.
Technically, yes, but the two checks are for very different things. Practically
speaking, there can never be false negatives without KVM breaking horribly as
overlap between struct page pfns and KVM's error/noslot would prevent mapping
legal memory into a KVM guest. But I'd rather not hide the "did KVM find a valid
mapping" in the "is this pfn backed by struct page" check, especially since this
code goes away entirely by the end of the series.
next prev parent reply other threads:[~2023-03-15 19:24 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-11 0:22 [PATCH v2 00/27] drm/i915/gvt: KVM: KVMGT fixes and page-track cleanups Sean Christopherson
2023-03-11 0:22 ` [PATCH v2 01/27] drm/i915/gvt: Verify pfn is "valid" before dereferencing "struct page" Sean Christopherson
2023-03-13 15:37 ` Wang, Wei W
2023-03-15 18:13 ` [Intel-gfx] " Andrzej Hajda
2023-03-15 19:23 ` Sean Christopherson [this message]
2023-03-17 4:20 ` Yan Zhao
2023-03-11 0:22 ` [PATCH v2 02/27] KVM: x86/mmu: Factor out helper to get max mapping size of a memslot Sean Christopherson
2023-03-13 15:37 ` Wang, Wei W
2023-03-11 0:22 ` [PATCH v2 03/27] drm/i915/gvt: remove interface intel_gvt_is_valid_gfn Sean Christopherson
2023-03-17 4:26 ` Yan Zhao
2023-03-11 0:22 ` [PATCH v2 04/27] drm/i915/gvt: Incorporate KVM memslot info into check for 2MiB GTT entry Sean Christopherson
2023-03-14 3:09 ` Yan Zhao
2023-03-14 17:13 ` Sean Christopherson
2023-03-11 0:22 ` [PATCH v2 05/27] drm/i915/gvt: Verify VFIO-pinned page is THP when shadowing 2M gtt entry Sean Christopherson
2023-03-17 5:33 ` Yan Zhao
2023-05-04 20:41 ` Sean Christopherson
2023-05-06 6:35 ` Yan Zhao
2023-05-06 10:57 ` Yan Zhao
2023-05-08 14:05 ` Sean Christopherson
2023-03-11 0:22 ` [PATCH v2 06/27] drm/i915/gvt: Put the page reference obtained by KVM's gfn_to_pfn() Sean Christopherson
2023-03-17 6:18 ` Yan Zhao
2023-03-11 0:22 ` [PATCH v2 07/27] drm/i915/gvt: Don't rely on KVM's gfn_to_pfn() to query possible 2M GTT Sean Christopherson
2023-03-17 5:37 ` Yan Zhao
2023-03-11 0:22 ` [PATCH v2 08/27] drm/i915/gvt: Use an "unsigned long" to iterate over memslot gfns Sean Christopherson
2023-03-17 6:19 ` Yan Zhao
2023-03-11 0:22 ` [PATCH v2 09/27] drm/i915/gvt: Drop unused helper intel_vgpu_reset_gtt() Sean Christopherson
2023-03-17 6:20 ` Yan Zhao
2023-03-11 0:22 ` [PATCH v2 10/27] drm/i915/gvt: Protect gfn hash table with vgpu_lock Sean Christopherson
2023-03-17 6:21 ` Yan Zhao
2023-03-11 0:22 ` [PATCH v2 11/27] KVM: x86/mmu: Don't rely on page-track mechanism to flush on memslot change Sean Christopherson
2023-03-15 1:08 ` Yan Zhao
2023-03-15 15:32 ` Sean Christopherson
2023-03-11 0:22 ` [PATCH v2 12/27] KVM: x86/mmu: Don't bounce through page-track mechanism for guest PTEs Sean Christopherson
2023-03-17 6:37 ` Yan Zhao
2023-03-11 0:22 ` [PATCH v2 13/27] KVM: drm/i915/gvt: Drop @vcpu from KVM's ->track_write() hook Sean Christopherson
2023-03-17 7:28 ` Yan Zhao
2023-03-11 0:22 ` [PATCH v2 14/27] KVM: x86: Reject memslot MOVE operations if KVMGT is attached Sean Christopherson
2023-03-15 8:03 ` Yan Zhao
2023-03-15 15:43 ` Sean Christopherson
2023-03-16 9:27 ` Yan Zhao
2023-03-17 7:29 ` Yan Zhao
2023-03-11 0:22 ` [PATCH v2 15/27] drm/i915/gvt: Don't bother removing write-protection on to-be-deleted slot Sean Christopherson
2023-03-17 7:30 ` Yan Zhao
2023-03-11 0:22 ` [PATCH v2 16/27] KVM: x86: Add a new page-track hook to handle memslot deletion Sean Christopherson
2023-03-17 7:43 ` Yan Zhao
2023-03-17 16:20 ` Sean Christopherson
2023-03-11 0:22 ` [PATCH v2 17/27] drm/i915/gvt: switch from ->track_flush_slot() to ->track_remove_region() Sean Christopherson
2023-03-17 7:45 ` Yan Zhao
2023-03-11 0:22 ` [PATCH v2 18/27] KVM: x86: Remove the unused page-track hook track_flush_slot() Sean Christopherson
2023-03-11 0:22 ` [PATCH v2 19/27] KVM: x86/mmu: Move KVM-only page-track declarations to internal header Sean Christopherson
2023-03-15 8:44 ` Yan Zhao
2023-03-15 15:13 ` Sean Christopherson
2023-03-16 9:19 ` Yan Zhao
2023-03-11 0:22 ` [PATCH v2 20/27] KVM: x86/mmu: Use page-track notifiers iff there are external users Sean Christopherson
2023-03-15 9:34 ` Yan Zhao
2023-03-15 16:21 ` Sean Christopherson
2023-03-16 9:29 ` Yan Zhao
2023-03-15 10:36 ` Yan Zhao
2023-03-15 16:54 ` Sean Christopherson
2023-05-04 19:54 ` Sean Christopherson
2023-05-06 1:08 ` Yan Zhao
2023-03-11 0:22 ` [PATCH v2 21/27] KVM: x86/mmu: Drop infrastructure for multiple page-track modes Sean Christopherson
2023-03-11 0:22 ` [PATCH v2 22/27] KVM: x86/mmu: Rename page-track APIs to reflect the new reality Sean Christopherson
2023-03-11 0:22 ` [PATCH v2 23/27] KVM: x86/mmu: Assert that correct locks are held for page write-tracking Sean Christopherson
2023-03-17 7:55 ` Yan Zhao
2023-03-11 0:22 ` [PATCH v2 24/27] KVM: x86/mmu: Bug the VM if write-tracking is used but not enabled Sean Christopherson
2023-03-11 0:22 ` [PATCH v2 25/27] KVM: x86/mmu: Drop @slot param from exported/external page-track APIs Sean Christopherson
2023-03-17 8:28 ` Yan Zhao
2023-03-23 8:50 ` Yan Zhao
2023-05-03 23:16 ` Sean Christopherson
2023-05-04 2:17 ` Yan Zhao
2023-05-08 1:15 ` Yan Zhao
2023-05-11 22:39 ` Sean Christopherson
2023-05-12 2:58 ` Yan Zhao
2023-03-11 0:22 ` [PATCH v2 26/27] KVM: x86/mmu: Handle KVM bookkeeping in page-track APIs, not callers Sean Christopherson
2023-03-17 8:52 ` Yan Zhao
2023-03-11 0:22 ` [PATCH v2 27/27] drm/i915/gvt: Drop final dependencies on KVM internal details Sean Christopherson
2023-03-17 8:58 ` Yan Zhao
2023-03-13 9:58 ` [PATCH v2 00/27] drm/i915/gvt: KVM: KVMGT fixes and page-track cleanups Yan Zhao
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