linux-kernel - Re: [PATCH v4 2/3] arm64: Add missing

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: <21F82E44-6D93-4F4C-8991-F14948673F54@oracle.com>
Date:   Thu, 19 Oct 2023 13:23:09 +0000
From:   Miguel Luis <miguel.luis@...cle.com>
To:     Marc Zyngier <maz@...nel.org>
CC:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Oliver Upton <oliver.upton@...ux.dev>,
        James Morse <james.morse@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Zenghui Yu <yuzenghui@...wei.com>,
        Jing Zhang <jingzhangos@...gle.com>,
        Eric Auger <eric.auger@...hat.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvmarm@...ts.linux.dev" <kvmarm@...ts.linux.dev>
Subject: Re: [PATCH v4 2/3] arm64: Add missing _EL2 encodings

Hi Marc,

> On 19 Oct 2023, at 11:39, Marc Zyngier <maz@...nel.org> wrote:
> 
> On Mon, 16 Oct 2023 12:17:41 +0100,
> Miguel Luis <miguel.luis@...cle.com> wrote:
>> 
>> Some _EL2 encodings are missing. Add them.
>> 
>> Signed-off-by: Miguel Luis <miguel.luis@...cle.com>
>> ---
>> arch/arm64/include/asm/sysreg.h | 39 +++++++++++++++++++++++++++++++++
>> 1 file changed, 39 insertions(+)
>> 
>> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
>> index ba5db50effec..8653fb67a339 100644
>> --- a/arch/arm64/include/asm/sysreg.h
>> +++ b/arch/arm64/include/asm/sysreg.h
> 
> [...]
> 
>> +#define SYS_SDER32_EL2 sys_reg(3, 4, 1, 3, 1)
> 
> [...]
> 
>> +#define SYS_VSTTBR_EL2 sys_reg(3, 4, 2, 6, 0)
>> +#define SYS_VSTCR_EL2 sys_reg(3, 4, 2, 6, 2)
> 
> [...]
> 
>> +#define SYS_CNTHVS_TVAL_EL2 sys_reg(3, 4, 14, 4, 0)
>> +#define SYS_CNTHVS_CTL_EL2 sys_reg(3, 4, 14, 4, 1)
>> +#define SYS_CNTHVS_CVAL_EL2 sys_reg(3, 4, 14, 4, 2)
>> +#define SYS_CNTHPS_TVAL_EL2 sys_reg(3, 4, 14, 5, 0)
>> +#define SYS_CNTHPS_CTL_EL2 sys_reg(3, 4, 14, 5, 1)
>> +#define SYS_CNTHPS_CVAL_EL2 sys_reg(3, 4, 14, 5, 2)
> 
> While the secure definitions seem correct, what is the rationale
> behind their presence here? They cannot be trapped from non-secure,
> and the pseudocode is pretty explicit:
> 
> if !IsCurrentSecurityState(SS_Secure) then
> UNDEFINED;
> 
> Given that, they cannot be trapped, handled or accessed from a KVM
> guest, as Linux on arm64 *always* runs non-secure.
> 

Thank you for clarifying.

Those definitions were needed for the refinement on patch 3 which clearly
didn’t considered that statement beforehand.

Yet, should we keep them here so they could be used?

Thank you
Miguel

> M.
> 
> -- 
> Without deviation from the norm, progress is not possible.