[xen] Add basic support for PV-HVM domains

Add basic support for Xen PV-HVM domains (detected via the Xen
platform PCI device with IDs 5853:0001), including support for
accessing configuration via XenStore and enumerating devices via
XenBus.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

9 files changed, 444 insertions, 0 deletions

diff --git a/src/include/ipxe/device.h b/src/include/ipxe/device.h
index 89509734..7202a696 100644
--- a/src/include/ipxe/device.h
+++ b/src/include/ipxe/device.h
@@ -60,6 +60,9 @@ struct device_description {
 /** EFI bus type */
 #define BUS_TYPE_EFI 7
 
+/** Xen bus type */
+#define BUS_TYPE_XEN 8
+
 /** A hardware device */
 struct device {
 	/** Name */
diff --git a/src/include/ipxe/errfile.h b/src/include/ipxe/errfile.h
index a8b3a8e4..3fa499dd 100644
--- a/src/include/ipxe/errfile.h
+++ b/src/include/ipxe/errfile.h
@@ -301,6 +301,9 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #define ERRFILE_memmap_settings	      ( ERRFILE_OTHER | 0x003f0000 )
 #define ERRFILE_param_cmd	      ( ERRFILE_OTHER | 0x00400000 )
 #define ERRFILE_deflate		      ( ERRFILE_OTHER | 0x00410000 )
+#define ERRFILE_xenstore	      ( ERRFILE_OTHER | 0x00420000 )
+#define ERRFILE_xenbus		      ( ERRFILE_OTHER | 0x00430000 )
+#define ERRFILE_xengrant	      ( ERRFILE_OTHER | 0x00440000 )
 
 /** @} */
 
diff --git a/src/include/ipxe/xen.h b/src/include/ipxe/xen.h
new file mode 100644
index 00000000..546b0c34
--- /dev/null
+++ b/src/include/ipxe/xen.h
@@ -0,0 +1,73 @@
+#ifndef _IPXE_XEN_H
+#define _IPXE_XEN_H
+
+/** @file
+ *
+ * Xen interface
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/* Define Xen interface version before including any Xen header files */
+#define __XEN_INTERFACE_VERSION__ 0x00040400
+
+#include <stdint.h>
+#include <ipxe/uaccess.h>
+#include <xen/xen.h>
+#include <xen/event_channel.h>
+
+/* Memory barrier macros used by ring.h */
+#define xen_mb() mb()
+#define xen_rmb() rmb()
+#define xen_wmb() wmb()
+
+struct xen_hypercall;
+
+/** A Xen grant table */
+struct xen_grant {
+	/** Grant table entries */
+	union grant_entry_v2 *table;
+	/** Number of grant table entries (must be a power of two) */
+	unsigned int count;
+	/** Number of grant table entries in use */
+	unsigned int used;
+	/** Most recently used grant reference */
+	unsigned int ref;
+};
+
+/** A XenStore */
+struct xen_store {
+	/** XenStore domain interface */
+	struct xenstore_domain_interface *intf;
+	/** Event channel */
+	evtchn_port_t port;
+};
+
+/** A Xen hypervisor */
+struct xen_hypervisor {
+	/** Hypercall table */
+	struct xen_hypercall *hypercall;
+	/** Shared info page */
+	struct shared_info *shared;
+	/** Grant table */
+	struct xen_grant grant;
+	/** XenStore */
+	struct xen_store store;
+};
+
+#include <bits/xen.h>
+
+/**
+ * Convert a Xen status code to an iPXE status code
+ *
+ * @v xenrc		Xen status code (negated)
+ * @ret rc		iPXE status code (before negation)
+ *
+ * Xen status codes are defined in the file include/xen/errno.h in the
+ * Xen repository.  They happen to match the Linux error codes, some
+ * of which can be found in our include/ipxe/errno/linux.h.
+ */
+#define EXEN( xenrc ) EPLATFORM ( EINFO_EPLATFORM, -(xenrc) )
+
+#endif /* _IPXE_XEN_H */
diff --git a/src/include/ipxe/xenbus.h b/src/include/ipxe/xenbus.h
new file mode 100644
index 00000000..2777226f
--- /dev/null
+++ b/src/include/ipxe/xenbus.h
@@ -0,0 +1,85 @@
+#ifndef _IPXE_XENBUS_H
+#define _IPXE_XENBUS_H
+
+/** @file
+ *
+ * Xen device bus
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <ipxe/device.h>
+#include <ipxe/tables.h>
+#include <ipxe/xen.h>
+#include <xen/io/xenbus.h>
+
+/** A Xen device */
+struct xen_device {
+	/** Generic iPXE device */
+	struct device dev;
+	/** Xen hypervisor */
+	struct xen_hypervisor *xen;
+	/** XenStore key */
+	char *key;
+	/** Backend XenStore key */
+	char *backend;
+	/** Backend domain ID */
+	unsigned long backend_id;
+	/** Driver */
+	struct xen_driver *driver;
+	/** Driver-private data */
+	void *priv;
+};
+
+/** A Xen device driver */
+struct xen_driver {
+	/** Name */
+	const char *name;
+	/** Device type */
+	const char *type;
+	/** Probe device
+	 *
+	 * @v xendev		Xen device
+	 * @ret rc		Return status code
+	 */
+	int ( * probe ) ( struct xen_device *xendev );
+	/** Remove device
+	 *
+	 * @v xendev		Xen device
+	 */
+	void ( * remove ) ( struct xen_device *xendev );
+};
+
+/** Xen device driver table */
+#define XEN_DRIVERS __table ( struct xen_driver, "xen_drivers" )
+
+/** Declare a Xen device driver */
+#define __xen_driver __table_entry ( XEN_DRIVERS, 01 )
+
+/**
+ * Set Xen device driver-private data
+ *
+ * @v xendev		Xen device
+ * @v priv		Private data
+ */
+static inline void xen_set_drvdata ( struct xen_device *xendev, void *priv ) {
+	xendev->priv = priv;
+}
+
+/**
+ * Get Xen device driver-private data
+ *
+ * @v xendev		Xen device
+ * @ret priv		Private data
+ */
+static inline void * xen_get_drvdata ( struct xen_device *xendev ) {
+	return xendev->priv;
+}
+
+extern int xenbus_set_state ( struct xen_device *xendev, int state );
+extern int xenbus_backend_wait ( struct xen_device *xendev, int state );
+extern int xenbus_probe ( struct xen_hypervisor *xen, struct device *parent );
+extern void xenbus_remove ( struct xen_hypervisor *xen, struct device *parent );
+
+#endif /* _IPXE_XENBUS_H */
diff --git a/src/include/ipxe/xenevent.h b/src/include/ipxe/xenevent.h
new file mode 100644
index 00000000..1dd6a0c0
--- /dev/null
+++ b/src/include/ipxe/xenevent.h
@@ -0,0 +1,59 @@
+#ifndef _IPXE_XENEVENT_H
+#define _IPXE_XENEVENT_H
+
+/** @file
+ *
+ * Xen events
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <ipxe/xen.h>
+#include <xen/event_channel.h>
+
+/**
+ * Close event channel
+ *
+ * @v xen		Xen hypervisor
+ * @v close		Event descriptor
+ * @ret xenrc		Xen status code
+ */
+static inline __attribute__ (( always_inline )) int
+xenevent_close ( struct xen_hypervisor *xen, struct evtchn_close *close ) {
+
+	return xen_hypercall_2 ( xen, __HYPERVISOR_event_channel_op,
+				 EVTCHNOP_close, virt_to_phys ( close ) );
+}
+
+/**
+ * Send event
+ *
+ * @v xen		Xen hypervisor
+ * @v send		Event descriptor
+ * @ret xenrc		Xen status code
+ */
+static inline __attribute__ (( always_inline )) int
+xenevent_send ( struct xen_hypervisor *xen, struct evtchn_send *send ) {
+
+	return xen_hypercall_2 ( xen, __HYPERVISOR_event_channel_op,
+				 EVTCHNOP_send, virt_to_phys ( send ) );
+}
+
+/**
+ * Allocate an unbound event channel
+ *
+ * @v xen		Xen hypervisor
+ * @v alloc_unbound	Event descriptor
+ * @ret xenrc		Xen status code
+ */
+static inline __attribute__ (( always_inline )) int
+xenevent_alloc_unbound ( struct xen_hypervisor *xen,
+			 struct evtchn_alloc_unbound *alloc_unbound ) {
+
+	return xen_hypercall_2 ( xen, __HYPERVISOR_event_channel_op,
+				 EVTCHNOP_alloc_unbound,
+				 virt_to_phys ( alloc_unbound ) );
+}
+
+#endif /* _IPXE_XENEVENT_H */
diff --git a/src/include/ipxe/xengrant.h b/src/include/ipxe/xengrant.h
new file mode 100644
index 00000000..776eb927
--- /dev/null
+++ b/src/include/ipxe/xengrant.h
@@ -0,0 +1,102 @@
+#ifndef _IPXE_XENGRANT_H
+#define _IPXE_XENGRANT_H
+
+/** @file
+ *
+ * Xen grant tables
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdint.h>
+#include <ipxe/io.h>
+#include <ipxe/xen.h>
+#include <xen/grant_table.h>
+
+/**
+ * Query grant table size
+ *
+ * @v xen		Xen hypervisor
+ * @v size		Table size
+ * @ret xenrc		Xen status code
+ */
+static inline __attribute__ (( always_inline )) int
+xengrant_query_size ( struct xen_hypervisor *xen,
+		      struct gnttab_query_size *size ) {
+
+	return xen_hypercall_3 ( xen, __HYPERVISOR_grant_table_op,
+				 GNTTABOP_query_size,
+				 virt_to_phys ( size ), 1 );
+}
+
+/**
+ * Set grant table version
+ *
+ * @v xen		Xen hypervisor
+ * @v version		Version
+ * @ret xenrc		Xen status code
+ */
+static inline __attribute__ (( always_inline )) int
+xengrant_set_version ( struct xen_hypervisor *xen,
+		       struct gnttab_set_version *version ) {
+
+	return xen_hypercall_3 ( xen, __HYPERVISOR_grant_table_op,
+				 GNTTABOP_set_version,
+				 virt_to_phys ( version ), 1 );
+}
+
+/**
+ * Invalidate access to a page
+ *
+ * @v xen		Xen hypervisor
+ * @v ref		Grant reference
+ */
+static inline __attribute__ (( always_inline )) void
+xengrant_invalidate ( struct xen_hypervisor *xen, grant_ref_t ref ) {
+	union grant_entry_v2 *entry = &xen->grant.table[ref];
+
+	/* Sanity check */
+	assert ( ( readw ( &entry->hdr.flags ) &
+		   ( GTF_reading | GTF_writing ) ) == 0 );
+
+	/* This should apparently be done using a cmpxchg instruction.
+	 * We omit this: partly in the interests of simplicity, but
+	 * mainly since our control flow generally does not permit
+	 * failure paths to themselves fail.
+	 */
+	writew ( 0, &entry->hdr.flags );
+}
+
+/**
+ * Permit access to a page
+ *
+ * @v xen		Xen hypervisor
+ * @v ref		Grant reference
+ * @v domid		Domain ID
+ * @v subflags		Additional flags
+ * @v page		Page start
+ */
+static inline __attribute__ (( always_inline )) void
+xengrant_permit_access ( struct xen_hypervisor *xen, grant_ref_t ref,
+			 domid_t domid, unsigned int subflags, void *page ) {
+	union grant_entry_v2 *entry = &xen->grant.table[ref];
+	unsigned long frame = ( virt_to_phys ( page ) / PAGE_SIZE );
+
+	writew ( domid, &entry->full_page.hdr.domid );
+	if ( sizeof ( physaddr_t ) == sizeof ( uint64_t ) ) {
+		writeq ( frame, &entry->full_page.frame );
+	} else {
+		writel ( frame, &entry->full_page.frame );
+	}
+	wmb();
+	writew ( ( GTF_permit_access | subflags ), &entry->full_page.hdr.flags);
+	wmb();
+}
+
+extern int xengrant_alloc ( struct xen_hypervisor *xen, grant_ref_t *refs,
+			    unsigned int count );
+extern void xengrant_free ( struct xen_hypervisor *xen, grant_ref_t *refs,
+			    unsigned int count );
+
+#endif /* _IPXE_XENGRANT_H */
diff --git a/src/include/ipxe/xenmem.h b/src/include/ipxe/xenmem.h
new file mode 100644
index 00000000..9b9aeda9
--- /dev/null
+++ b/src/include/ipxe/xenmem.h
@@ -0,0 +1,46 @@
+#ifndef _IPXE_XENMEM_H
+#define _IPXE_XENMEM_H
+
+/** @file
+ *
+ * Xen memory operations
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <ipxe/xen.h>
+#include <xen/memory.h>
+
+/**
+ * Add page to physical address space
+ *
+ * @v xen		Xen hypervisor
+ * @v add		Page mapping descriptor
+ * @ret xenrc		Xen status code
+ */
+static inline __attribute__ (( always_inline )) int
+xenmem_add_to_physmap ( struct xen_hypervisor *xen,
+			struct xen_add_to_physmap *add ) {
+
+	return xen_hypercall_2 ( xen, __HYPERVISOR_memory_op,
+				 XENMEM_add_to_physmap, virt_to_phys ( add ) );
+}
+
+/**
+ * Remove page from physical address space
+ *
+ * @v xen		Xen hypervisor
+ * @v remove		Page mapping descriptor
+ * @ret xenrc		Xen status code
+ */
+static inline __attribute__ (( always_inline )) int
+xenmem_remove_from_physmap ( struct xen_hypervisor *xen,
+			     struct xen_remove_from_physmap *remove ) {
+
+	return xen_hypercall_2 ( xen, __HYPERVISOR_memory_op,
+				 XENMEM_remove_from_physmap,
+				 virt_to_phys ( remove ) );
+}
+
+#endif /* _IPXE_XENMEM_H */
diff --git a/src/include/ipxe/xenstore.h b/src/include/ipxe/xenstore.h
new file mode 100644
index 00000000..f25f1570
--- /dev/null
+++ b/src/include/ipxe/xenstore.h
@@ -0,0 +1,29 @@
+#ifndef _IPXE_XENSTORE_H
+#define _IPXE_XENSTORE_H
+
+/** @file
+ *
+ * XenStore interface
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <ipxe/xen.h>
+
+extern __attribute__ (( sentinel )) int
+xenstore_read ( struct xen_hypervisor *xen, char **value, ... );
+extern __attribute__ (( sentinel )) int
+xenstore_read_num ( struct xen_hypervisor *xen, unsigned long *num, ... );
+extern __attribute__ (( sentinel )) int
+xenstore_write ( struct xen_hypervisor *xen, const char *value, ... );
+extern __attribute__ (( sentinel )) int
+xenstore_write_num ( struct xen_hypervisor *xen, unsigned long num, ... );
+extern __attribute__ (( sentinel )) int
+xenstore_rm ( struct xen_hypervisor *xen, ... );
+extern __attribute__ (( sentinel )) int
+xenstore_directory ( struct xen_hypervisor *xen, char **children, size_t *len,
+		     ... );
+extern void xenstore_dump ( struct xen_hypervisor *xen, const char *key );
+
+#endif /* _IPXE_XENSTORE_H */
diff --git a/src/include/ipxe/xenver.h b/src/include/ipxe/xenver.h
new file mode 100644
index 00000000..5d678c5a
--- /dev/null
+++ b/src/include/ipxe/xenver.h
@@ -0,0 +1,44 @@
+#ifndef _IPXE_XENVER_H
+#define _IPXE_VENVER_H
+
+/** @file
+ *
+ * Xen version
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <ipxe/xen.h>
+#include <xen/version.h>
+
+/**
+ * Get Xen version
+ *
+ * @v xen		Xen hypervisor
+ * @ret version		Version (major.minor: 16 bits each)
+ */
+static inline __attribute__ (( always_inline )) uint32
+xenver_version ( struct xen_hypervisor *xen ) {
+
+	return xen_hypercall_2 ( xen, __HYPERVISOR_xen_version,
+				 XENVER_version, 0 );
+}
+
+/**
+ * Get Xen extra version string
+ *
+ * @v xen		Xen hypervisor
+ * @v extraversion	Extra version string to fill in
+ * @ret xenrc		Xen status code
+ */
+static inline __attribute__ (( always_inline )) int
+xenver_extraversion ( struct xen_hypervisor *xen,
+		      xen_extraversion_t *extraversion ) {
+
+	return xen_hypercall_2 ( xen, __HYPERVISOR_xen_version,
+				 XENVER_extraversion,
+				 virt_to_phys ( extraversion ) );
+}
+
+#endif /* _IPXE_XENVER_H */