From e6aa2b85a9aecba0e19c5fe82e93f46f107ec7e9 Mon Sep 17 00:00:00 2001
From: Zenithal <i@zenithal.me>
Date: Wed, 17 May 2023 23:44:43 +0800
Subject: [PATCH] [module] AMD SEV support

---
 AUTHORS        |  1 +
 module/kvmfr.c | 27 +++++++++++++++++++++++++--
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/AUTHORS b/AUTHORS
index 247753d6..76f72fc7 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -66,3 +66,4 @@ David Meier <meier_david_91@hotmail.com> (Kenny.ch)
 Daniel Cordero <looking-glass@0xdc.io> (0xdc)
 esi <git@esibun.net> (esibun)
 MakiseKurisu <saberconer@gmail.com> (MakiseKurisu)
+Zenithal <i@zenithal.me> (ZenithalHourlyRate)
diff --git a/module/kvmfr.c b/module/kvmfr.c
index c711e000..32162aaf 100644
--- a/module/kvmfr.c
+++ b/module/kvmfr.c
@@ -1,6 +1,6 @@
 /**
  * Looking Glass
- * Copyright © 2017-2022 The Looking Glass Authors
+ * Copyright © 2017-2023 The Looking Glass Authors
  * https://looking-glass.io
  *
  * This program is free software; you can redistribute it and/or modify it
@@ -33,6 +33,10 @@
 
 #include <asm/io.h>
 
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+#include <asm/mem_encrypt.h>
+#endif
+
 #include "kvmfr.h"
 
 DEFINE_MUTEX(minor_lock);
@@ -321,6 +325,25 @@ static int device_mmap(struct file * filp, struct vm_area_struct * vma)
   switch (kdev->type)
   {
     case KVMFR_TYPE_PCI:
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+      /* Clear C-bit for ivshmem when mapped
+       * as normal memory to the userspace
+       *
+       * devm_memremap below will "hotplug" the ivshmem as normal mem,
+       * when sev and/or sev-snp is effective,
+       * ivshmem will be encrypted and private memory.
+       *
+       * However, this is not the intention of ivshmem, as it
+       * is meant to be shared with other VMs and the hypervisor.
+       *
+       * Mapping ivshmem as iomem could resolve the sev/sev-snp issue,
+       * but it then will not be cached and the performance is low.
+       *
+       * To maintain high performance yet make it shared, we should
+       * clear the C-bit for ivshmem.
+       */
+      vma->vm_page_prot.pgprot &= ~(sme_me_mask);
+#endif
       vma->vm_ops          = &pci_mmap_ops;
       vma->vm_private_data = kdev;
       return 0;
@@ -626,7 +649,7 @@ MODULE_DEVICE_TABLE(pci, kvmfr_pci_ids);
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Geoffrey McRae <geoff@hostfission.com>");
 MODULE_AUTHOR("Guanzhong Chen <quantum2048@gmail.com>");
-MODULE_VERSION("0.0.8");
+MODULE_VERSION("0.0.9");
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(5,16,0)
 MODULE_IMPORT_NS(DMA_BUF);
 #endif