From: Sean Christopherson seanjc@google.com
commit a9545779ee9e9e103648f6f2552e73cfe808d0f4 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 bd2fae8da794 ("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: add6a0cd1c5b ("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: Ben Hutchings ben@decadent.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- virt/kvm/kvm_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1518,7 +1518,7 @@ static int hva_to_pfn_remapped(struct vm bool write_fault, bool *writable, kvm_pfn_t *p_pfn) { - unsigned long pfn; + kvm_pfn_t pfn; pte_t *ptep; spinlock_t *ptl; int r;