linux-kernel - Re: [PATCH 4.19 111/120] KVM: do not assume PTE is writable after follow

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Message-ID: <CADVatmOcg_7eQno88nu4ijX9QOoA0h2QY=hoj3TZU+tNqj0TMg@mail.gmail.com>
Date:   Mon, 26 Jul 2021 22:17:47 +0100
From:   Sudip Mukherjee <sudipm.mukherjee@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        Stable <stable@...r.kernel.org>,
        David Stevens <stevensd@...gle.com>, 3pvd@...gle.com,
        Jann Horn <jannh@...gle.com>, Jason Gunthorpe <jgg@...pe.ca>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Ovidiu Panait <ovidiu.panait@...driver.com>
Subject: Re: [PATCH 4.19 111/120] KVM: do not assume PTE is writable after follow_pfn

Hi Greg,

On Mon, Jul 26, 2021 at 4:58 PM Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> From: Paolo Bonzini <pbonzini@...hat.com>
>
> 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


-- 
Regards
Sudip