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

Christoph Hellwig
2022-03-14T07:32:36Z

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