On Tue, Jul 27, 2021 at 01:01:01PM +0200, Paolo Bonzini wrote:
> On 27/07/21 10:29, Ovidiu Panait wrote:
> > From: Sean Christopherson <seanjc@xxxxxxxxxx>
> >
> > 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@xxxxxxxxxxxxxxx
> > Fixes: add6a0cd1c5b ("KVM: MMU: try to fix up page faults before giving up")
> > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> > Message-Id: <20210208201940.1258328-1-seanjc@xxxxxxxxxx>
> > Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> > Signed-off-by: Ovidiu Panait <ovidiu.panait@xxxxxxxxxxxxx>
> > ---
> > virt/kvm/kvm_main.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > index 3559eba5f502..a3d82113ae1c 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -1501,7 +1501,7 @@ 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;
> >
>
> Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
>
> and the other two are the same as v1.
Thanks, now queued up. I'll push out a new -rc with this added.
greg k-h
