Drivers: hv: vmbus: Remove second mapping of VMBus monitor pages

With changes to how Hyper-V guest VMs flip memory between private
(encrypted) and shared (decrypted), creating a second kernel virtual
mapping for shared memory is no longer necessary.  Everything needed
for the transition to shared is handled by set_memory_decrypted().

As such, remove the code to create and manage the second
mapping for VMBus monitor pages. Because set_memory_decrypted()
and set_memory_encrypted() are no-ops in normal VMs, it's
not even necessary to test for being in a Confidential VM
(a.k.a., "Isolation VM").

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Link: https://lore.kernel.org/r/1679838727-87310-9-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index da51b50787dff39ef697b82d4e8f8708c39c9ce0..5978e9dbc286fbbc17ed15e3a0c5e395c4925c9e 100644 (file)
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -104,8 +104,14 @@ int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
                vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
        }
 
-       msg->monitor_page1 = vmbus_connection.monitor_pages_pa[0];
-       msg->monitor_page2 = vmbus_connection.monitor_pages_pa[1];
+       /*
+        * shared_gpa_boundary is zero in non-SNP VMs, so it's safe to always
+        * bitwise OR it
+        */
+       msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]) |
+                               ms_hyperv.shared_gpa_boundary;
+       msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]) |
+                               ms_hyperv.shared_gpa_boundary;
 
        msg->target_vcpu = hv_cpu_number_to_vp_number(VMBUS_CONNECT_CPU);
 
@@ -219,72 +225,27 @@ int vmbus_connect(void)
         * Setup the monitor notification facility. The 1st page for
         * parent->child and the 2nd page for child->parent
         */
-       vmbus_connection.monitor_pages[0] = (void *)hv_alloc_hyperv_zeroed_page();
-       vmbus_connection.monitor_pages[1] = (void *)hv_alloc_hyperv_zeroed_page();
+       vmbus_connection.monitor_pages[0] = (void *)hv_alloc_hyperv_page();
+       vmbus_connection.monitor_pages[1] = (void *)hv_alloc_hyperv_page();
        if ((vmbus_connection.monitor_pages[0] == NULL) ||
            (vmbus_connection.monitor_pages[1] == NULL)) {
                ret = -ENOMEM;
                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);
+       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;
 
-       }
+       /*
+        * Set_memory_decrypted() will change the memory contents if
+        * decryption occurs, 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),
@@ -376,31 +337,13 @@ void vmbus_disconnect(void)
                vmbus_connection.int_page = 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);
-       }
+       set_memory_encrypted((unsigned long)vmbus_connection.monitor_pages[0], 1);
+       set_memory_encrypted((unsigned long)vmbus_connection.monitor_pages[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;
+       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;
 }
 
 /*

diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index dc673edf053c3b7dc6f086f946a3290242c90a36..167ac5115a78945255ef9bc4f4aeb8f206e25b34 100644 (file)
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -241,8 +241,6 @@ 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;