[PATCH 08/15] x86: centralize setting SWIOTLB_FORCE when guest memory encryption is enabled

[Christoph Hellwig <hch@lst.de>]

Move enabling SWIOTLB_FORCE for guest memory encryption into common code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/x86/kernel/cpu/mshyperv.c | 8 --------
 arch/x86/kernel/pci-dma.c      | 8 ++++++++
 arch/x86/mm/mem_encrypt_amd.c  | 3 ---
 3 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 5a99f993e6392..568274917f1cd 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -336,14 +336,6 @@ static void __init ms_hyperv_init_platform(void)
 			swiotlb_unencrypted_base = ms_hyperv.shared_gpa_boundary;
 #endif
 		}
-
-#ifdef CONFIG_SWIOTLB
-		/*
-		 * Enable swiotlb force mode in Isolation VM to
-		 * use swiotlb bounce buffer for dma transaction.
-		 */
-		swiotlb_force = SWIOTLB_FORCE;
-#endif
 	}
 
 	if (hv_max_functions_eax >= HYPERV_CPUID_NESTED_FEATURES) {
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index df96926421be0..04140e20ef1a3 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -53,6 +53,14 @@ static void __init pci_swiotlb_detect(void)
 	if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT))
 		x86_swiotlb_enable = true;
 
+	/*
+	 * Guest with guest memory encryption currently perform all DMA through
+	 * bounce buffers as the hypervisor can't access arbitrary VM memory
+	 * that is not explicitly shared with it.
+	 */
+	if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
+		swiotlb_force = SWIOTLB_FORCE;
+
 	if (swiotlb_force == SWIOTLB_FORCE)
 		x86_swiotlb_enable = true;
 }
diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c
index 2b2d018ea3450..a72942d569cf9 100644
--- a/arch/x86/mm/mem_encrypt_amd.c
+++ b/arch/x86/mm/mem_encrypt_amd.c
@@ -191,9 +191,6 @@ void __init sme_early_init(void)
 	/* Update the protection map with memory encryption mask */
 	for (i = 0; i < ARRAY_SIZE(protection_map); i++)
 		protection_map[i] = pgprot_encrypted(protection_map[i]);
-
-	if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
-		swiotlb_force = SWIOTLB_FORCE;
 }
 
 void __init sev_setup_arch(void)
-- 
2.30.2