Drivers: hv: vmbus: Add SNP support for VMbus channel initiate message

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.

Reviewed-by: Michael Kelley <[email protected]>
Signed-off-by: Tianyu Lan <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Wei Liu <[email protected]>

Author: Tianyu Lan

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 +365,31 @@ 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() checks input address is ioremap address or not
+		 * inside. It doesn't unmap any thing in the non-SNP CVM and
+		 * so not check CVM type here.
+		 */
+		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;
 }
 
 /*

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;