Sean Christopherson 4ae7392ab6 KVM: MMU: Do not treat ZONE_DEVICE pages as being reserved ... commit a78986aae9 upstream. Explicitly exempt ZONE_DEVICE pages from kvm_is_reserved_pfn() and instead manually handle ZONE_DEVICE on a case-by-case basis. For things like page refcounts, KVM needs to treat ZONE_DEVICE pages like normal pages, e.g. put pages grabbed via gup(). But for flows such as setting A/D bits or shifting refcounts for transparent huge pages, KVM needs to to avoid processing ZONE_DEVICE pages as the flows in question lack the underlying machinery for proper handling of ZONE_DEVICE pages. This fixes a hang reported by Adam Borowski[*] in dev_pagemap_cleanup() when running a KVM guest backed with /dev/dax memory, as KVM straight up doesn't put any references to ZONE_DEVICE pages acquired by gup(). Note, Dan Williams proposed an alternative solution of doing put_page() on ZONE_DEVICE pages immediately after gup() in order to simplify the auditing needed to ensure is_zone_device_page() is called if and only if the backing device is pinned (via gup()). But that approach would break kvm_vcpu_{un}map() as KVM requires the page to be pinned from map() 'til unmap() when accessing guest memory, unlike KVM's secondary MMU, which coordinates with mmu_notifier invalidations to avoid creating stale page references, i.e. doesn't rely on pages being pinned. [*] http://lkml.kernel.org/r/20190919115547.GA17963@angband.pl Reported-by: Adam Borowski <kilobyte@angband.pl> Analyzed-by: David Hildenbrand <david@redhat.com> Acked-by: Dan Williams <dan.j.williams@intel.com> Cc: stable@vger.kernel.org Fixes: 3565fce3a6 ("mm, x86: get_user_pages() for dax mappings") Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> [sean: backport to 4.x; resolve conflict in mmu.c] Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2019-12-01 09:17:35 +01:00
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arm	kvm: arm/arm64: Fix stage2_flush_memslot for 4 level page table	2019-11-24 08:19:31 +01:00
async_pf.c	sched/swait: Rename to exclusive	2018-06-20 11:35:56 +02:00
async_pf.h	KVM: fix checkpatch.pl errors in kvm/async_pf.h	2015-06-19 17:16:25 +02:00
coalesced_mmio.c	KVM: coalesced_mmio: add bounds checking	2019-09-21 07:16:44 +02:00
coalesced_mmio.h	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
eventfd.c	kvm: Check irqchip mode before assign irqfd	2019-09-16 08:22:15 +02:00
irqchip.c	KVM: fix spectrev1 gadgets	2019-05-16 19:41:22 +02:00
Kconfig	KVM: arm64: Prevent KVM_COMPAT from being selected	2018-06-21 17:17:50 +01:00
kvm_main.c	KVM: MMU: Do not treat ZONE_DEVICE pages as being reserved	2019-12-01 09:17:35 +01:00
vfio.c	vfio: New external user group/file match	2017-06-28 13:50:05 -06:00
vfio.h	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00