On 2021-03-04 00:46, Justin He wrote:
Hi Marc
-----Original Message-----
From: Will Deacon <will@xxxxxxxxxx>
Sent: Thursday, March 4, 2021 5:13 AM
To: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Justin He <Justin.He@xxxxxxx>; kvmarm@xxxxxxxxxxxxxxxxxxxxx; James
Morse <James.Morse@xxxxxxx>; Julien Thierry
<julien.thierry.kdev@xxxxxxxxx>;
Suzuki Poulose <Suzuki.Poulose@xxxxxxx>; Catalin Marinas
<Catalin.Marinas@xxxxxxx>; Gavin Shan <gshan@xxxxxxxxxx>; Yanan Wang
<wangyanan55@xxxxxxxxxx>; Quentin Perret <qperret@xxxxxxxxxx>;
linux-arm-
kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
Subject: Re: [PATCH] KVM: arm64: Fix unaligned addr case in mmu
walking
On Wed, Mar 03, 2021 at 07:07:37PM +0000, Marc Zyngier wrote:
> From e0524b41a71e0f17d6dc8f197e421e677d584e72 Mon Sep 17 00:00:00 2001
> From: Jia He <justin.he@xxxxxxx>
> Date: Wed, 3 Mar 2021 10:42:25 +0800
> Subject: [PATCH] KVM: arm64: Fix range alignment when walking page tables
>
> When walking the page tables at a given level, and if the start
> address for the range isn't aligned for that level, we propagate
> the misalignment on each iteration at that level.
>
> This results in the walker ignoring a number of entries (depending
> on the original misalignment) on each subsequent iteration.
>
> Properly aligning the address at the before the next iteration
"at the before the next" ???
> addresses the issue.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Reported-by: Howard Zhang <Howard.Zhang@xxxxxxx>
> Signed-off-by: Jia He <justin.he@xxxxxxx>
> Fixes: b1e57de62cfb ("KVM: arm64: Add stand-alone page-table walker
infrastructure")
> [maz: rewrite commit message]
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> Link: https://lore.kernel.org/r/20210303024225.2591-1-justin.he@xxxxxxx
> ---
> arch/arm64/kvm/hyp/pgtable.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index 4d177ce1d536..124cd2f93020 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -223,7 +223,7 @@ static inline int __kvm_pgtable_visit(struct
kvm_pgtable_walk_data *data,
> goto out;
>
> if (!table) {
> - data->addr += kvm_granule_size(level);
> + data->addr = ALIGN(data->addr, kvm_granule_size(level));
What if previous data->addr is already aligned with
kvm_granule_size(level)?
Hence a deadloop? Am I missing anything else?
Indeed, well spotted. I'll revert to your original suggestion
if everybody agrees...
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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