linux-kernel - Re: [PATCH v3 1/3] KVM: arm64: Add flags to kvm_hyp

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Message-ID: <87r0327iek.wl-maz@kernel.org>
Date: Wed, 12 Mar 2025 08:38:43 +0000
From: Marc Zyngier <maz@...nel.org>
To: Vincent Donnefort <vdonnefort@...gle.com>
Cc: oliver.upton@...ux.dev,
	joey.gouly@....com,
	suzuki.poulose@....com,
	yuzenghui@...wei.com,
	catalin.marinas@....com,
	will@...nel.org,
	qperret@...gle.com,
	linux-arm-kernel@...ts.infradead.org,
	kvmarm@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	kernel-team@...roid.com
Subject: Re: [PATCH v3 1/3] KVM: arm64: Add flags to kvm_hyp_memcache

On Fri, 07 Mar 2025 11:34:09 +0000,
Vincent Donnefort <vdonnefort@...gle.com> wrote:
> 
> Add flags to kvm_hyp_memcache and propagate the latter to the allocation
> and free callbacks. This will later allow to account for memory, based
> on the memcache configuration.
> 
> Signed-off-by: Vincent Donnefort <vdonnefort@...gle.com>
> 
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 3a7ec98ef123..12691ae23d4c 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -86,6 +86,7 @@ struct kvm_hyp_memcache {
>  	phys_addr_t head;
>  	unsigned long nr_pages;
>  	struct pkvm_mapping *mapping; /* only used from EL1 */
> +	unsigned long flags;
>  };
>  
>  static inline void push_hyp_memcache(struct kvm_hyp_memcache *mc,
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 1f55b0c7b11d..c01ad4430729 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -1086,12 +1086,12 @@ void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu)
>  	}
>  }
>  
> -static void hyp_mc_free_fn(void *addr, void *unused)
> +static void hyp_mc_free_fn(void *addr, void *mc)
>  {
>  	free_page((unsigned long)addr);
>  }
>  
> -static void *hyp_mc_alloc_fn(void *unused)
> +static void *hyp_mc_alloc_fn(void *mc)
>  {
>  	return (void *)__get_free_page(GFP_KERNEL_ACCOUNT);
>  }
> @@ -1102,7 +1102,7 @@ void free_hyp_memcache(struct kvm_hyp_memcache *mc)
>  		return;
>  
>  	kfree(mc->mapping);
> -	__free_hyp_memcache(mc, hyp_mc_free_fn, kvm_host_va, NULL);
> +	__free_hyp_memcache(mc, hyp_mc_free_fn, kvm_host_va, (void *)mc);

Why the cast? It looks superfluous to me.

>  }
>  
>  int topup_hyp_memcache(struct kvm_hyp_memcache *mc, unsigned long min_pages)
> @@ -1117,7 +1117,7 @@ int topup_hyp_memcache(struct kvm_hyp_memcache *mc, unsigned long min_pages)
>  	}
>  
>  	return __topup_hyp_memcache(mc, min_pages, hyp_mc_alloc_fn,
> -				    kvm_host_pa, NULL);
> +				    kvm_host_pa, (void *)mc);

Same here.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.