Subject: Re: [RFC PATCH 09/45] KVM: arm64: pkvm: Add pkvm_create_hyp_device_mapping()

From: Mostafa Saleh <[email-masked]>
Date: Tue, 7 Feb 2023 12:22:13 +0000

Hi Jean,

On Wed, Feb 01, 2023 at 12:52:53PM +0000, Jean-Philippe Brucker wrote:
> Add a function to map a MMIO region in the hypervisor and remove it from
> the host. Hypervisor device drivers use this to reserve their regions
> during setup.
> 
> Signed-off-by: Jean-Philippe Brucker <[email-masked]>
> ---
>  arch/arm64/kvm/hyp/include/nvhe/mm.h |  1 +
>  arch/arm64/kvm/hyp/nvhe/setup.c      | 17 +++++++++++++++++
>  2 files changed, 18 insertions(+)
> 
> diff --git a/arch/arm64/kvm/hyp/include/nvhe/mm.h b/arch/arm64/kvm/hyp/include/nvhe/mm.h
> index d5ec972b5c1e..84db840f2057 100644
> --- a/arch/arm64/kvm/hyp/include/nvhe/mm.h
> +++ b/arch/arm64/kvm/hyp/include/nvhe/mm.h
> @@ -27,5 +27,6 @@ int __pkvm_create_private_mapping(phys_addr_t phys, size_t size,
>  				  enum kvm_pgtable_prot prot,
>  				  unsigned long *haddr);
>  int pkvm_alloc_private_va_range(size_t size, unsigned long *haddr);
> +int pkvm_create_hyp_device_mapping(u64 base, u64 size, void __iomem *haddr);
>  
>  #endif /* __KVM_HYP_MM_H */
> diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
> index 629e74c46b35..de7d60c3c20b 100644
> --- a/arch/arm64/kvm/hyp/nvhe/setup.c
> +++ b/arch/arm64/kvm/hyp/nvhe/setup.c
> @@ -259,6 +259,23 @@ static int fix_host_ownership(void)
>  	return 0;
>  }
>  
> +/* Map the MMIO region into the hypervisor and remove it from host */
> +int pkvm_create_hyp_device_mapping(u64 base, u64 size, void __iomem *haddr)
> +{
> +	int ret;
> +
> +	ret = __pkvm_create_private_mapping(base, size, PAGE_HYP_DEVICE, haddr);
> +	if (ret)
> +		return ret;
> +
> +	/* lock not needed during setup */
> +	ret = host_stage2_set_owner_locked(base, size, PKVM_ID_HYP);
> +	if (ret)
> +		return ret;
> +

Do we need to unmap in case of errors from host_stage2_set_owner_locked?

> +	return ret;
> +}
> +
>  static int fix_hyp_pgtable_refcnt(void)
>  {
>  	struct kvm_pgtable_walker walker = {
> -- 
> 2.39.0
> 

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