It was found that AWS SEV-SNP enabled instances are not able to boot with commit 81256a50aa0f ("x86/mm: Make memremap(MEMREMAP_WB) map memory as encrypted by default") applied and the reason seems to be the vmgenid device which requires unencrypted writeable memory. A similar problem was previously fixed in DRM with commit 7dfede7d7edd ("drm/vmwgfx: Fix guests running with TDX/SEV"). Note, trusting vmgenid device in a Confidential VM is questionable: the malicious host may intentionally avoid notifying the guest when a copy is created. Fixes: 81256a50aa0f ("x86/mm: Make memremap(MEMREMAP_WB) map memory as encrypted by default") Signed-off-by: Vitaly Kuznetsov --- drivers/virt/vmgenid.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/virt/vmgenid.c b/drivers/virt/vmgenid.c index 66135eac3abf..2cf0096aa217 100644 --- a/drivers/virt/vmgenid.c +++ b/drivers/virt/vmgenid.c @@ -75,7 +75,8 @@ static int vmgenid_add_acpi(struct device *dev, struct vmgenid_state *state) phys_addr = (obj->package.elements[0].integer.value << 0) | (obj->package.elements[1].integer.value << 32); - virt_addr = devm_memremap(&device->dev, phys_addr, VMGENID_SIZE, MEMREMAP_WB); + virt_addr = devm_memremap(&device->dev, phys_addr, VMGENID_SIZE, + MEMREMAP_WB | MEMREMAP_DEC); if (IS_ERR(virt_addr)) { ret = PTR_ERR(virt_addr); goto out; -- 2.52.0