From: Will Deacon <will@kernel.org>
To: Ard Biesheuvel <ardb@google.com>
Cc: linux-arm-kernel@lists.infradead.org,
Ard Biesheuvel <ardb@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Marc Zyngier <maz@kernel.org>,
Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH v2 1/3] arm64: Avoid enabling KPTI unnecessarily
Date: Mon, 27 Nov 2023 15:48:18 +0000 [thread overview]
Message-ID: <20231127154818.GA8453@willie-the-truck> (raw)
In-Reply-To: <20231127120049.2258650-6-ardb@google.com>
On Mon, Nov 27, 2023 at 01:00:51PM +0100, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@kernel.org>
>
> Commit 42c5a3b04bf6 refactored the KPTI init code in a way that results
> in the use of non-global kernel mappings even on systems that have no
> need for it, and even when KPTI has been disabled explicitly via the
> command line.
>
> Ensure that this only happens when we have decided (based on the
> detected system-wide CPU features) that KPTI should be enabled.
>
> Fixes: 42c5a3b04bf6 ("arm64: Split kpti_install_ng_mappings()")
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
> arch/arm64/kernel/cpufeature.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 646591c67e7a..91d2d6714969 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -1839,6 +1839,10 @@ static int __init __kpti_install_ng_mappings(void *__unused)
>
> static void __init kpti_install_ng_mappings(void)
> {
> + /* Check whether KPTI is going to be used */
> + if (!cpus_have_cap(ARM64_UNMAP_KERNEL_AT_EL0))
> + return;
Why can't you use arm64_kernel_unmapped_at_el0() here?
Will
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next prev parent reply other threads:[~2023-11-27 15:48 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-27 12:00 [PATCH v2 0/3] arm64 kpti fixes Ard Biesheuvel
2023-11-27 12:00 ` [PATCH v2 1/3] arm64: Avoid enabling KPTI unnecessarily Ard Biesheuvel
2023-11-27 15:48 ` Will Deacon [this message]
2023-11-27 15:52 ` Ard Biesheuvel
2023-11-27 16:31 ` Will Deacon
2023-11-27 16:39 ` Ard Biesheuvel
2023-11-27 16:41 ` Will Deacon
2023-11-27 17:49 ` Mark Rutland
2023-11-28 11:03 ` Will Deacon
2023-11-28 14:13 ` Mark Rutland
2023-12-11 11:39 ` Will Deacon
2023-12-12 17:16 ` Mark Rutland
2023-11-28 11:06 ` Will Deacon
2023-11-27 12:00 ` [PATCH v2 2/3] arm64: mm: Only map KPTI trampoline if it is going to be used Ard Biesheuvel
2023-11-27 12:00 ` [PATCH v2 3/3] arm64: Kconfig: drop KAISER reference from KPTI option description Ard Biesheuvel
2023-11-27 12:47 ` [PATCH v2 0/3] arm64 kpti fixes Mark Rutland
2023-11-30 19:14 ` (subset) " Catalin Marinas
2023-12-11 20:27 ` Will Deacon
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