Re: [PATCH 4.19 111/120] KVM: do not assume PTE is writable after follow_pfn

[Paolo Bonzini]

On 26/07/21 23:17, Sudip Mukherjee wrote:
> Hi Greg,
>
> On Mon, Jul 26, 2021 at 4:58 PM Greg Kroah-Hartman
> <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> > From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> >
> > commit bd2fae8da794b55bf2ac02632da3a151b10e664c upstream.
>
> The build of mips malta_kvm_defconfig fails with the error:
> In file included from arch/mips/kvm/../../../virt/kvm/kvm_main.c:21:
> arch/mips/kvm/../../../virt/kvm/kvm_main.c: In function 'hva_to_pfn_remapped':
> ./include/linux/kvm_host.h:70:33: error: conversion from 'long long
> unsigned int' to 'long unsigned int' changes value from
> '9218868437227405314' to '2' [-Werror=overflow]
>     70 | #define KVM_PFN_ERR_RO_FAULT    (KVM_PFN_ERR_MASK + 2)
>        |                                 ^
> arch/mips/kvm/../../../virt/kvm/kvm_main.c:1530:23: note: in expansion
> of macro 'KVM_PFN_ERR_RO_FAULT'
>   1530 |                 pfn = KVM_PFN_ERR_RO_FAULT;
>
> It built fine after reverting this patch.
> gcc version 11.1.1 20210723

I'll resend a version that works tomorrow (including the second patch 
too, which depends on this one for context).

Paolo