s390/uv: introduce guest side ultravisor code

The Ultravisor Call Facility (stfle bit 158) defines an API to the
Ultravisor (UV calls), a mini hypervisor located at machine
level. With help of the Ultravisor, KVM will be able to run
"protected" VMs, special VMs whose memory and management data are
unavailable to KVM.

The protected VMs can also request services from the Ultravisor.
The guest api consists of UV calls to share and unshare memory with the
kvm hypervisor.

To enable this feature support PROTECTED_VIRTUALIZATION_GUEST kconfig
option has been introduced.

Co-developed-by: Janosch Frank <frankja@de.ibm.com>
Signed-off-by: Janosch Frank <frankja@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 27 insertions, 0 deletions

diff --git a/arch/s390/boot/Makefile b/arch/s390/boot/Makefile
index 458d18c44c67..a5ae68b2aa84 100644
--- a/arch/s390/boot/Makefile
+++ b/arch/s390/boot/Makefile
@@ -30,6 +30,7 @@ CFLAGS_sclp_early_core.o += -I$(srctree)/drivers/s390/char
 
 obj-y	:= head.o als.o startup.o mem_detect.o ipl_parm.o string.o ebcdic.o
 obj-y	+= sclp_early_core.o mem.o ipl_vmparm.o cmdline.o ctype.o
+obj-$(CONFIG_PROTECTED_VIRTUALIZATION_GUEST)	+= uv.o
 targets	:= bzImage startup.a section_cmp.boot.data section_cmp.boot.preserved.data $(obj-y)
 subdir-	:= compressed
 
diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c
index 57d7f9446e29..2bd4a62d436c 100644
--- a/arch/s390/boot/startup.c
+++ b/arch/s390/boot/startup.c
@@ -2,6 +2,7 @@
 #include <linux/string.h>
 #include <asm/setup.h>
 #include <asm/sclp.h>
+#include <asm/uv.h>
 #include "compressed/decompressor.h"
 #include "boot.h"
 
@@ -53,6 +54,7 @@ void startup_kernel(void)
 {
 	void *img;
 
+	uv_query_info();
 	rescue_initrd();
 	sclp_early_read_info();
 	store_ipl_parmblock();
diff --git a/arch/s390/boot/uv.c b/arch/s390/boot/uv.c
new file mode 100644
index 000000000000..ed007f4a6444
--- /dev/null
+++ b/arch/s390/boot/uv.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <asm/uv.h>
+#include <asm/facility.h>
+#include <asm/sections.h>
+
+int __bootdata_preserved(prot_virt_guest);
+
+void uv_query_info(void)
+{
+	struct uv_cb_qui uvcb = {
+		.header.cmd = UVC_CMD_QUI,
+		.header.len = sizeof(uvcb)
+	};
+
+	if (!test_facility(158))
+		return;
+
+	if (uv_call(0, (uint64_t)&uvcb))
+		return;
+
+	if (test_bit_inv(BIT_UVC_CMD_SET_SHARED_ACCESS, (unsigned long *)uvcb.inst_calls_list) &&
+	    test_bit_inv(BIT_UVC_CMD_REMOVE_SHARED_ACCESS, (unsigned long *)uvcb.inst_calls_list))
+		prot_virt_guest = 1;
+}