linux-stable/virt
Sean Christopherson ff7f4da1dc KVM: Use kvm_pfn_t for local PFN variable in hva_to_pfn_remapped()
commit a9545779ee upstream.

Use kvm_pfn_t, a.k.a. u64, for the local 'pfn' variable when retrieving
a so called "remapped" hva/pfn pair.  In theory, the hva could resolve to
a pfn in high memory on a 32-bit kernel.

This bug was inadvertantly exposed by commit bd2fae8da7 ("KVM: do not
assume PTE is writable after follow_pfn"), which added an error PFN value
to the mix, causing gcc to comlain about overflowing the unsigned long.

  arch/x86/kvm/../../../virt/kvm/kvm_main.c: In function ‘hva_to_pfn_remapped’:
  include/linux/kvm_host.h:89:30: error: conversion from ‘long long unsigned int’
                                  to ‘long unsigned int’ changes value from
                                  ‘9218868437227405314’ to ‘2’ [-Werror=overflow]
   89 | #define KVM_PFN_ERR_RO_FAULT (KVM_PFN_ERR_MASK + 2)
      |                              ^
virt/kvm/kvm_main.c:1935:9: note: in expansion of macro ‘KVM_PFN_ERR_RO_FAULT’

Cc: stable@vger.kernel.org
Fixes: add6a0cd1c ("KVM: MMU: try to fix up page faults before giving up")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210208201940.1258328-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-08-08 08:53:29 +02:00
..
kvm KVM: Use kvm_pfn_t for local PFN variable in hva_to_pfn_remapped() 2021-08-08 08:53:29 +02:00
lib KVM: eventfd: fix NULL deref irqbypass consumer 2017-01-12 14:42:34 +01:00
Makefile virt: Add virt directory to the top Makefile 2015-10-01 15:06:44 +02:00