linux-kernel - Re: [PATCH v8 01/26] arm64: Fix HCR.TGE status for NMI contexts

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20190114155634.GB84430@arrakis.emea.arm.com>
Date:   Mon, 14 Jan 2019 15:56:35 +0000
From:   Catalin Marinas <catalin.marinas@....com>
To:     Julien Thierry <julien.thierry@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, mark.rutland@....com,
        linux-arch@...r.kernel.org, daniel.thompson@...aro.org,
        Arnd Bergmann <arnd@...db.de>, marc.zyngier@....com,
        will.deacon@....com, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, christoffer.dall@....com,
        james.morse@....com, joel@...lfernandes.org
Subject: Re: [PATCH v8 01/26] arm64: Fix HCR.TGE status for NMI contexts

On Tue, Jan 08, 2019 at 02:07:19PM +0000, Julien Thierry wrote:
> When using VHE, the host needs to clear HCR_EL2.TGE bit in order
> to interract with guest TLBs, switching from EL2&0 translation regime
> to EL1&0.
> 
> However, some non-maskable asynchronous event could happen while TGE is
> cleared like SDEI. Because of this address translation operations
> relying on EL2&0 translation regime could fail (tlb invalidation,
> userspace access, ...).

Why would an NMI context need to access user space? (just curious what
breaks exactly without this patch; otherwise it looks fine)

-- 
Catalin