[RFC PATCH kernel 10/17] x86, dma: Allow accepted devices to map private memory

[Alexey Kardashevskiy <aik@xxxxxxx>]

From: Dan Williams <dan.j.williams@xxxxxxxxx>

With the arrival of "accepted" devices, devices that have been enabled to
DMA to private encrypted memory, coherent DMA allocation no longer requires
page conversion. Update force_dma_unencrypted() to skip accepted devices.

Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
[aik: re-added device_cc_accepted()]
Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxx>
---
 arch/x86/mm/mem_encrypt.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index 95bae74fdab2..805800ddbd79 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -20,10 +20,11 @@
 bool force_dma_unencrypted(struct device *dev)
 {
        /*
-        * For SEV, all DMA must be to unencrypted addresses.
+        * Require unencrypted DMA unless the device has been "accepted",
+        * enabled by a TSM driver to DMA to private encrypted memory.
         */
        if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
-               return true;
+               return !__device_cc_accepted(dev);
 
        /*
         * For SME, all DMA must be to unencrypted addresses if the
-- 
2.55.0