From 0ffe039d7eb51f4620fe4cb83b9f14d1a85365e7 Mon Sep 17 00:00:00 2001
From: Thomas Hellstrom <thellstrom@vmware.com>
Date: Thu, 14 Nov 2019 13:03:18 +0000
Subject: drm/vmwgfx: Don't use the HB port if memory encryption is active
Git-commit: af4eaf10978e5b14660020f39e619059489cc694
Patch-mainline: v5.6-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
With memory encryption active, the hypervisor typically can't read the
guest memory using the HB port, since it is encrypted using a key known
only to the guest. In that case fall back to processing 4 bytes at a time
using the ordinary backdoor port.
The other option would be to use unencrypted bounce buffers for the
hypervisor to read out from or write into, but given the limited message
sizes it appears more efficient to just fall back to the ordinary backdoor
port.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/vmwgfx/vmwgfx_msg.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c b/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c
index b6c5e4c2ac3c..d63441194249 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c
@@ -28,6 +28,7 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
+#include <linux/mem_encrypt.h>
#include <asm/hypervisor.h>
@@ -148,7 +149,8 @@ static unsigned long vmw_port_hb_out(struct rpc_channel *channel,
unsigned long si, di, eax, ebx, ecx, edx;
unsigned long msg_len = strlen(msg);
- if (hb) {
+ /* HB port can't access encrypted memory. */
+ if (hb && !mem_encrypt_active()) {
unsigned long bp = channel->cookie_high;
si = (uintptr_t) msg;
@@ -202,7 +204,8 @@ static unsigned long vmw_port_hb_in(struct rpc_channel *channel, char *reply,
{
unsigned long si, di, eax, ebx, ecx, edx;
- if (hb) {
+ /* HB port can't access encrypted memory */
+ if (hb && !mem_encrypt_active()) {
unsigned long bp = channel->cookie_low;
si = channel->cookie_high;
--
2.28.0