The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From a9545779ee9e9e103648f6f2552e73cfe808d0f4 Mon Sep 17 00:00:00 2001

From: Sean Christopherson seanjc@google.com Date: Mon, 8 Feb 2021 12:19:40 -0800 Subject: [PATCH] KVM: Use kvm_pfn_t for local PFN variable in hva_to_pfn_remapped() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

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

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index ee4ac2618ec5..001b9de4e727 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1906,7 +1906,7 @@ static int hva_to_pfn_remapped(struct vm_area_struct *vma, 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;