[PATCH 2/2] x86/hyperv: Set swiotlb_alloc_from_low_pages to false

[Tianyu Lan <ltykernel@gmail.com>]

From: Tianyu Lan <Tianyu.Lan@microsoft.com>

In Hyper-V Isolation VM, swiotlb bnounce buffer size maybe 1G at most
and there maybe no enough memory from 0 to 4G according to memory layout.
Devices in Isolation VM can use memory above 4G as DMA memory. Set swiotlb_
alloc_from_low_pages to false in Isolation VM.

Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
---
 arch/x86/kernel/cpu/mshyperv.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 5a99f993e639..80a0423ac75d 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -343,6 +343,7 @@ static void __init ms_hyperv_init_platform(void)
 		 * use swiotlb bounce buffer for dma transaction.
 		 */
 		swiotlb_force = SWIOTLB_FORCE;
+		swiotlb_alloc_from_low_pages = false;
 #endif
 	}
 
-- 
2.25.1