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Message-ID: <20240208131938.GB23428@willie-the-truck>
Date: Thu, 8 Feb 2024 13:19:39 +0000
From: Will Deacon <will@...nel.org>
To: ankita@...dia.com
Cc: jgg@...dia.com, maz@...nel.org, oliver.upton@...ux.dev,
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Subject: Re: [PATCH v6 1/4] kvm: arm64: introduce new flag for non-cacheable
IO memory
On Thu, Feb 08, 2024 at 02:16:49AM +0530, ankita@...dia.com wrote:
> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index c651df904fe3..2a893724ee9b 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -717,15 +717,28 @@ void kvm_tlb_flush_vmid_range(struct kvm_s2_mmu *mmu,
> static int stage2_set_prot_attr(struct kvm_pgtable *pgt, enum kvm_pgtable_prot prot,
> kvm_pte_t *ptep)
> {
> - bool device = prot & KVM_PGTABLE_PROT_DEVICE;
> - kvm_pte_t attr = device ? KVM_S2_MEMATTR(pgt, DEVICE_nGnRE) :
> - KVM_S2_MEMATTR(pgt, NORMAL);
> + kvm_pte_t attr;
> u32 sh = KVM_PTE_LEAF_ATTR_LO_S2_SH_IS;
>
> + switch (prot & (KVM_PGTABLE_PROT_DEVICE |
> + KVM_PGTABLE_PROT_NORMAL_NC)) {
> + case 0:
> + attr = KVM_S2_MEMATTR(pgt, NORMAL);
> + break;
> + case KVM_PGTABLE_PROT_DEVICE:
> + if (prot & KVM_PGTABLE_PROT_X)
> + return -EINVAL;
> + attr = KVM_S2_MEMATTR(pgt, DEVICE_nGnRE);
> + break;
> + case KVM_PGTABLE_PROT_NORMAL_NC:
> + attr = KVM_S2_MEMATTR(pgt, NORMAL_NC);
> + break;
> + default:
> + WARN_ON_ONCE(1);
> + }
Cosmetic nit, but I'd find this a little easier to read if the normal
case was the default (i.e. drop 'case 0') and we returned an error for
DEVICE | NC.
Will
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