s390/mm: provide memory management functions for protected KVM guests

This provides the basic ultravisor calls and page table handling to cope
with secure guests:
- provide arch_make_page_accessible
- make pages accessible after unmapping of secure guests
- provide the ultravisor commands convert to/from secure
- provide the ultravisor commands pin/unpin shared
- provide callbacks to make pages secure (inacccessible)
 - we check for the expected pin count to only make pages secure if the
   host is not accessing them
 - we fence hugetlbfs for secure pages
- add missing radix-tree include into gmap.h

The basic idea is that a page can have 3 states: secure, normal or
shared. The hypervisor can call into a firmware function called
ultravisor that allows to change the state of a page: convert from/to
secure. The convert from secure will encrypt the page and make it
available to the host and host I/O. The convert to secure will remove
the host capability to access this page.
The design is that on convert to secure we will wait until writeback and
page refs are indicating no host usage. At the same time the convert
from secure (export to host) will be called in common code when the
refcount or the writeback bit is already set. This avoids races between
convert from and to secure.

Then there is also the concept of shared pages. Those are kind of secure
where the host can still access those pages. We need to be notified when
the guest "unshares" such a page, basically doing a convert to secure by
then. There is a call "pin shared page" that we use instead of convert
from secure when possible.

We do use PG_arch_1 as an optimization to minimize the convert from
secure/pin shared.

Several comments have been added in the code to explain the logic in
the relevant places.

Co-developed-by: Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
Signed-off-by: Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
[borntraeger@de.ibm.com: patch merging, splitting, fixing]
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index 1af6ce8023cc..d089a960b3e2 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -15,6 +15,7 @@
 #include <linux/errno.h>
 #include <linux/bug.h>
 #include <asm/page.h>
+#include <asm/gmap.h>
 
 #define UVC_RC_EXECUTED		0x0001
 #define UVC_RC_INV_CMD		0x0002
@@ -24,6 +25,10 @@
 
 #define UVC_CMD_QUI			0x0001
 #define UVC_CMD_INIT_UV			0x000f
+#define UVC_CMD_CONV_TO_SEC_STOR	0x0200
+#define UVC_CMD_CONV_FROM_SEC_STOR	0x0201
+#define UVC_CMD_PIN_PAGE_SHARED		0x0341
+#define UVC_CMD_UNPIN_PAGE_SHARED	0x0342
 #define UVC_CMD_SET_SHARED_ACCESS	0x1000
 #define UVC_CMD_REMOVE_SHARED_ACCESS	0x1001
 
@@ -31,8 +36,12 @@
 enum uv_cmds_inst {
 	BIT_UVC_CMD_QUI = 0,
 	BIT_UVC_CMD_INIT_UV = 1,
+	BIT_UVC_CMD_CONV_TO_SEC_STOR = 6,
+	BIT_UVC_CMD_CONV_FROM_SEC_STOR = 7,
 	BIT_UVC_CMD_SET_SHARED_ACCESS = 8,
 	BIT_UVC_CMD_REMOVE_SHARED_ACCESS = 9,
+	BIT_UVC_CMD_PIN_PAGE_SHARED = 21,
+	BIT_UVC_CMD_UNPIN_PAGE_SHARED = 22,
 };
 
 struct uv_cb_header {
@@ -69,6 +78,19 @@ struct uv_cb_init {
 	u64 reserved28[4];
 } __packed __aligned(8);
 
+struct uv_cb_cts {
+	struct uv_cb_header header;
+	u64 reserved08[2];
+	u64 guest_handle;
+	u64 gaddr;
+} __packed __aligned(8);
+
+struct uv_cb_cfs {
+	struct uv_cb_header header;
+	u64 reserved08[2];
+	u64 paddr;
+} __packed __aligned(8);
+
 struct uv_cb_share {
 	struct uv_cb_header header;
 	u64 reserved08[3];
@@ -171,12 +193,21 @@ static inline int is_prot_virt_host(void)
 	return prot_virt_host;
 }
 
+int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb);
+int uv_convert_from_secure(unsigned long paddr);
+int gmap_convert_to_secure(struct gmap *gmap, unsigned long gaddr);
+
 void setup_uv(void);
 void adjust_to_uv_max(unsigned long *vmax);
 #else
 #define is_prot_virt_host() 0
 static inline void setup_uv(void) {}
 static inline void adjust_to_uv_max(unsigned long *vmax) {}
+
+static inline int uv_convert_from_secure(unsigned long paddr)
+{
+	return 0;
+}
 #endif
 
 #if defined(CONFIG_PROTECTED_VIRTUALIZATION_GUEST) || IS_ENABLED(CONFIG_KVM)