Subject: Re: [PATCH 13/17] kvm-arm: Add stage2 page table modifiers
To: Christoffer Dall <christoffer.dall@linaro.org>
References: <1459787177-12767-1-git-send-email-suzuki.poulose@arm.com>
 <1459787177-12767-14-git-send-email-suzuki.poulose@arm.com>
 <20160408134257.GW8961@cbox> <5707D01E.1050309@arm.com>
 <20160408170302.GA13247@cbox>
Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
        marc.zyngier@arm.com, mark.rutland@arm.com, will.deacon@arm.com,
        catalin.marinas@arm.com
From: Suzuki K Poulose <Suzuki.Poulose@arm.com>
Message-ID: <5707E541.5040205@arm.com>
Date: Fri, 8 Apr 2016 18:07:13 +0100
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On 08/04/16 18:03, Christoffer Dall wrote:
> On Fri, Apr 08, 2016 at 04:37:02PM +0100, Suzuki K Poulose wrote:
>> On 08/04/16 14:42, Christoffer Dall wrote:
>>> On Mon, Apr 04, 2016 at 05:26:13PM +0100, Suzuki K Poulose wrote:
>>
>>>>
>>>> -static void clear_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr)
>>>> +static void clear_stage2_pud_entry(struct kvm *kvm, pud_t *pud, phys_addr_t addr)
>>>>   {
>>>> -	pmd_t *pmd_table = pmd_offset(pud, 0);
>>>> -	VM_BUG_ON(pud_huge(*pud));
>>>> -	pud_clear(pud);
>>>> +	pmd_t *pmd_table __maybe_unused = stage2_pmd_offset(pud, 0);
>>>
>>> The __maybe_unused are slightly ugly, so it may be nicer to create the
>>> stage2_pmd_free() as static inline's if they're defined to do nothing
>>> instead.
>>>
>>
>> Sure, we could do that for stage2. However, we will need to fix the host helpers
>> as well for making such a change in the _hyp version (for 16K + 36bit VA).
>>
>
> I thought the host helpers were already done like that, since we don't
> need the __maybe_unused currently.  If it involves changing core code
> etc. then don't bother.

Unfortunately no, e.g,

include/asm-generic/pgtable-nopud.h defines:

#define pud_free(mm, x)                         do { } while (0)

Cheers
Suzuki