Re: [PATCH v1 6/7] x86/kvm: Use bounce buffers for TD guest

[Tom Lendacky]

On 6/9/21 4:55 PM, Kuppuswamy Sathyanarayanan wrote:
> From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
> diff --git a/arch/x86/mm/mem_encrypt_common.c b/arch/x86/mm/mem_encrypt_common.c
> index 8053b43298ff..2da70f58b208 100644
> --- a/arch/x86/mm/mem_encrypt_common.c
> +++ b/arch/x86/mm/mem_encrypt_common.c
> @@ -9,6 +9,7 @@
>  
>  #include <asm/mem_encrypt_common.h>
>  #include <linux/dma-mapping.h>
> +#include <linux/swiotlb.h>
>  
>  /* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
>  bool force_dma_unencrypted(struct device *dev)
> @@ -21,3 +22,18 @@ bool force_dma_unencrypted(struct device *dev)
>  
>  	return false;
>  }
> +
> +/* Architecture __weak replacement functions */
> +void __init mem_encrypt_init(void)
> +{
> +	/*
> +	 * For TDX guest or SEV/SME, call into SWIOTLB to update
> +	 * the SWIOTLB DMA buffers
> +	 */
> +	if (sme_me_mask || prot_guest_has(PR_GUEST_MEM_ENCRYPT))
> +		swiotlb_update_mem_attributes();
> +
> +	if (sme_me_mask)
> +		amd_mem_encrypt_init();

The sme_me_mask is checked in amd_mem_encrypt_init(), so you should just
invoke amd_mem_encrypt_init() unconditionally.

Thanks,
Tom

> +}
> +
>