[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>

1 files changed, 102 insertions, 0 deletions

diff --git a/src/include/ipxe/xengrant.h b/src/include/ipxe/xengrant.h
new file mode 100644
index 000000000..776eb9273
--- /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 */