Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v9 15/18] arm64: kexec: kexec EL2 vectors
To:     Pavel Tatashin <pasha.tatashin@soleen.com>
References: <20200326032420.27220-1-pasha.tatashin@soleen.com>
 <20200326032420.27220-16-pasha.tatashin@soleen.com>
From:   James Morse <james.morse@arm.com>
Cc:     jmorris@namei.org, sashal@kernel.org, ebiederm@xmission.com,
        kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
        corbet@lwn.net, catalin.marinas@arm.com, will@kernel.org,
        linux-arm-kernel@lists.infradead.org, maz@kernel.org,
        vladimir.murzin@arm.com, matthias.bgg@gmail.com,
        bhsharma@redhat.com, linux-mm@kvack.org, mark.rutland@arm.com,
        steve.capper@arm.com, rfontana@redhat.com, tglx@linutronix.de,
        selindag@gmail.com
Message-ID: <c9b5897b-a4a3-0ec1-10d1-520c8b7c89cc@arm.com>
Date:   Thu, 7 May 2020 17:21:59 +0100
User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101
 Thunderbird/60.9.0
MIME-Version: 1.0
In-Reply-To: <20200326032420.27220-16-pasha.tatashin@soleen.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-GB
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Pavel,

What happened to the subject?
(it really needs a verb to make any sense)

On 26/03/2020 03:24, Pavel Tatashin wrote:
> If we have a EL2 mode without VHE, the EL2 vectors are needed in order
> to switch to EL2 and jump to new world with hyperivsor privileges.

Yes, but the hyp-stub has an API to let you do this... but you need your own version.

Could you explain why in the commit message?

(spelling: hyperivsor)


> diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
> index ab571fca9bd1..bd398def7627 100644
> --- a/arch/arm64/kernel/machine_kexec.c
> +++ b/arch/arm64/kernel/machine_kexec.c
> @@ -84,6 +84,11 @@ int machine_kexec_post_load(struct kimage *kimage)
>  	kern_reloc_arg->head = kimage->head;
>  	kern_reloc_arg->entry_addr = kimage->start;
>  	kern_reloc_arg->kern_arg0 = kimage->arch.dtb_mem;
> +	/* Setup vector table only when EL2 is available, but no VHE */
> +	if (is_hyp_mode_available() && !is_kernel_in_hyp_mode()) {
> +		kern_reloc_arg->el2_vector = __pa(reloc_code)
> +						+ kexec_el2_vectors_offset;
> +	}

Why does the asm relocation code need to know where the vector is? It must access it via HVC.


Thanks,

James