RE: [PATCH] swiotlb: add a SWIOTLB_ANY flag to lift restricted low memory for encryption

[Miao, Jun]

Hi maintainers and Big shot,
I would like to further explain my original intention:
The purpose is to solve the problem found by customers when inserting 8 NVMe disks - There will be a swiotlb buffer full warning. 
When CONFIG_SWIOTLB_DYNAMIC is turned on, it is impossible to allocate more than 2G swiotlb buffer to meet the actual high throughput usage requirements. 

Warm regards
Jun Miao
>
>TDX guest wants to allocate a swiotlb buffer that is not restricted to low memory
>for the trusted hypervisor scheme. So that allow to pick a location everywhere for
>hypervisors with guest memory encryption in
>swiotlb_memblock_alloc() interface by adding a new flag.
>
>Signed-off-by: Jun Miao <jun.miao@xxxxxxxxx>
>---
> arch/x86/kernel/pci-dma.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c index
>6267363e0189..73b9320c4a7d 100644
>--- a/arch/x86/kernel/pci-dma.c
>+++ b/arch/x86/kernel/pci-dma.c
>@@ -61,7 +61,7 @@ static void __init pci_swiotlb_detect(void)
> 	 */
> 	if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)) {
> 		x86_swiotlb_enable = true;
>-		x86_swiotlb_flags |= SWIOTLB_FORCE;
>+		x86_swiotlb_flags |= SWIOTLB_ANY | SWIOTLB_FORCE;
> 	}
> }
> #else
>--
>2.43.0