Subject: [PATCH V6 7/8] Drivers: hv: vmbus: Add SNP support for VMbus channel initiate message

From: Tianyu Lan <[email-masked]>
Date: Thu, 30 Sep 2021 09:05:43 -0400

From: Tianyu Lan <[email-masked]>

The monitor pages in the CHANNELMSG_INITIATE_CONTACT msg are shared
with host in Isolation VM and so it's necessary to use hvcall to set
them visible to host. In Isolation VM with AMD SEV SNP, the access
address should be in the extra space which is above shared gpa
boundary. So remap these pages into the extra address(pa +
shared_gpa_boundary).

Introduce monitor_pages_original[] in the struct vmbus_connection
to store monitor page virtual address returned by hv_alloc_hyperv_
zeroed_page() and free monitor page via monitor_pages_original in
the vmbus_disconnect(). The monitor_pages[] is to used to access
monitor page and it is initialized to be equal with monitor_pages_
original. The monitor_pages[] will be overridden in the isolation VM
with va of extra address. Introduce monitor_pages_pa[] to store
monitor pages' physical address and use it to populate pa in the
initiate msg.

Signed-off-by: Tianyu Lan <[email-masked]>
---
Change since v5:
	*  change vmbus_connection.monitor_pages_pa type from
	   unsigned long to phys_addr_t
	*  Plus vmbus_connection.monitor_pages_pa with ms_hyperv.
	   shared_gpa_boundary only in the IVM with AMD SEV.

Change since v4:
	* Introduce monitor_pages_pa[] to store monitor pages' physical
	  address and use it to populate pa in the initiate msg.
	* Move code of mapping moniter pages in extra address into
	  vmbus_connect().

Change since v3:
	* Rename monitor_pages_va with monitor_pages_original
	* free monitor page via monitor_pages_original and
	  monitor_pages is used to access monitor page.

Change since v1:
        * Not remap monitor pages in the non-SNP isolation VM.
---
 drivers/hv/connection.c   | 90 ++++++++++++++++++++++++++++++++++++---
 drivers/hv/hyperv_vmbus.h |  2 +
 2 files changed, 86 insertions(+), 6 deletions(-)

diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 8820ae68f20f..7fac8d99541c 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -19,6 +19,8 @@
 #include <linux/vmalloc.h>
 #include <linux/hyperv.h>
 #include <linux/export.h>
+#include <linux/io.h>
+#include <linux/set_memory.h>
 #include <asm/mshyperv.h>
 
 #include "hyperv_vmbus.h"
@@ -102,8 +104,9 @@ int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
 		vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
 	}
 
-	msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
-	msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
+	msg->monitor_page1 = vmbus_connection.monitor_pages_pa[0];
+	msg->monitor_page2 = vmbus_connection.monitor_pages_pa[1];
+
 	msg->target_vcpu = hv_cpu_number_to_vp_number(VMBUS_CONNECT_CPU);
 
 	/*
@@ -216,6 +219,65 @@ int vmbus_connect(void)
 		goto cleanup;
 	}
 
+	vmbus_connection.monitor_pages_original[0]
+		= vmbus_connection.monitor_pages[0];
+	vmbus_connection.monitor_pages_original[1]
+		= vmbus_connection.monitor_pages[1];
+	vmbus_connection.monitor_pages_pa[0]
+		= virt_to_phys(vmbus_connection.monitor_pages[0]);
+	vmbus_connection.monitor_pages_pa[1]
+		= virt_to_phys(vmbus_connection.monitor_pages[1]);
+
+	if (hv_is_isolation_supported()) {
+		ret = set_memory_decrypted((unsigned long)
+					   vmbus_connection.monitor_pages[0],
+					   1);
+		ret |= set_memory_decrypted((unsigned long)
+					    vmbus_connection.monitor_pages[1],
+					    1);
+		if (ret)
+			goto cleanup;
+
+		/*
+		 * Isolation VM with AMD SNP needs to access monitor page via
+		 * address space above shared gpa boundary.
+		 */
+		if (hv_isolation_type_snp()) {
+			vmbus_connection.monitor_pages_pa[0] +=
+				ms_hyperv.shared_gpa_boundary;
+			vmbus_connection.monitor_pages_pa[1] +=
+				ms_hyperv.shared_gpa_boundary;
+
+			vmbus_connection.monitor_pages[0]
+				= memremap(vmbus_connection.monitor_pages_pa[0],
+					   HV_HYP_PAGE_SIZE,
+					   MEMREMAP_WB);
+			if (!vmbus_connection.monitor_pages[0]) {
+				ret = -ENOMEM;
+				goto cleanup;
+			}
+
+			vmbus_connection.monitor_pages[1]
+				= memremap(vmbus_connection.monitor_pages_pa[1],
+					   HV_HYP_PAGE_SIZE,
+					   MEMREMAP_WB);
+			if (!vmbus_connection.monitor_pages[1]) {
+				ret = -ENOMEM;
+				goto cleanup;
+			}
+		}
+
+		/*
+		 * Set memory host visibility hvcall smears memory
+		 * and so zero monitor pages here.
+		 */
+		memset(vmbus_connection.monitor_pages[0], 0x00,
+		       HV_HYP_PAGE_SIZE);
+		memset(vmbus_connection.monitor_pages[1], 0x00,
+		       HV_HYP_PAGE_SIZE);
+
+	}
+
 	msginfo = kzalloc(sizeof(*msginfo) +
 			  sizeof(struct vmbus_channel_initiate_contact),
 			  GFP_KERNEL);
@@ -303,10 +365,26 @@ void vmbus_disconnect(void)
 		vmbus_connection.int_page = NULL;
 	}
 
-	hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[0]);
-	hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[1]);
-	vmbus_connection.monitor_pages[0] = NULL;
-	vmbus_connection.monitor_pages[1] = NULL;
+	if (hv_is_isolation_supported()) {
+		memunmap(vmbus_connection.monitor_pages[0]);
+		memunmap(vmbus_connection.monitor_pages[1]);
+
+		set_memory_encrypted((unsigned long)
+			vmbus_connection.monitor_pages_original[0],
+			1);
+		set_memory_encrypted((unsigned long)
+			vmbus_connection.monitor_pages_original[1],
+			1);
+	}
+
+	hv_free_hyperv_page((unsigned long)
+		vmbus_connection.monitor_pages_original[0]);
+	hv_free_hyperv_page((unsigned long)
+		vmbus_connection.monitor_pages_original[1]);
+	vmbus_connection.monitor_pages_original[0] =
+		vmbus_connection.monitor_pages[0] = NULL;
+	vmbus_connection.monitor_pages_original[1] =
+		vmbus_connection.monitor_pages[1] = NULL;
 }
 
 /*
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 42f3d9d123a1..d0a5232a1c3e 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -240,6 +240,8 @@ struct vmbus_connection {
 	 * is child->parent notification
 	 */
 	struct hv_monitor_page *monitor_pages[2];
+	void *monitor_pages_original[2];
+	phys_addr_t monitor_pages_pa[2];
 	struct list_head chn_msg_list;
 	spinlock_t channelmsg_lock;
 
-- 
2.25.1