From mboxrd@z Thu Jan  1 00:00:00 1970
From: James Morse <james.morse@arm.com>
Subject: Re: [PATCH v6 10/26] KVM: arm/arm64: Fix idmap size and alignment
Date: Thu, 15 Mar 2018 19:15:48 +0000
Message-ID: <5AAAC664.8070400@arm.com>
References: <20180314165049.30105-1-marc.zyngier@arm.com>
 <20180314165049.30105-11-marc.zyngier@arm.com>
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Cc: Mark Rutland <mark.rutland@arm.com>,
 Peter Maydell <peter.maydell@linaro.org>, Andrew Jones <drjones@redhat.com>,
 Christoffer Dall <cdall@kernel.org>, kvm@vger.kernel.org,
 Steve Capper <steve.capper@arm.com>, Catalin Marinas <catalin.marinas@arm.com>,
 Will Deacon <will.deacon@arm.com>,
 Kristina Martsenko <kristina.martsenko@arm.com>,
 linux-arm-kernel@lists.infradead.org
To: Marc Zyngier <marc.zyngier@arm.com>, kvmarm@lists.cs.columbia.edu
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On 14/03/18 16:50, Marc Zyngier wrote:
> Although the idmap section of KVM can only be at most 4kB and
> must be aligned on a 4kB boundary, the rest of the code expects
> it to be page aligned. Things get messy when tearing down the
> HYP page tables when PAGE_SIZE is 64K, and the idmap section isn't
> 64K aligned.
> 
> Let's fix this by computing aligned boundaries that the HYP code
> will use.

> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
> index 0e5cfffb4c21..a9e0513868e9 100644
> --- a/virt/kvm/arm/mmu.c
> +++ b/virt/kvm/arm/mmu.c
> @@ -1815,7 +1815,9 @@ int kvm_mmu_init(void)
>  	int err;
>  
>  	hyp_idmap_start = kvm_virt_to_phys(__hyp_idmap_text_start);
> +	hyp_idmap_start = ALIGN_DOWN(hyp_idmap_start, PAGE_SIZE);
>  	hyp_idmap_end = kvm_virt_to_phys(__hyp_idmap_text_end);
> +	hyp_idmap_end = ALIGN(hyp_idmap_end, PAGE_SIZE);
>  	hyp_idmap_vector = kvm_virt_to_phys(__kvm_hyp_init);
>  
>  	/*


This makes the:
| hyp_idmap_start != (unsigned long)__hyp_idmap_text_start

check below look funny, but that must be for 32bit which only has 4K pages (I
think), so its behaviour hasn't changed.

Reviewed-by: James Morse <james.morse@arm.com>


Thanks,

James