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Commit 8dca4d96 authored by Juergen Gross's avatar Juergen Gross Committed by Boris Ostrovsky
Browse files

xen: select grant interface version 



Grant v2 will be needed in cases where a frame number in the grant
table can exceed 32 bits. For PV guests this is a host feature, while
for HVM guests this is a guest feature.

So select grant v2 in case frame numbers can be larger than 32 bits
and grant v1 else.

For testing purposes add a way to specify the grant interface version
via a boot parameter.

Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Reviewed-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
parent 223c8f33

drivers/xen/grant-table.c

+33 −2
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ 


#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt



#include <linux/bootmem.h>

#include <linux/sched.h>

#include <linux/mm.h>

#include <linux/slab.h>
@@ -43,6 +44,7 @@ 
#include <linux/hardirq.h>

#include <linux/workqueue.h>

#include <linux/ratelimit.h>

#include <linux/moduleparam.h>



#include <xen/xen.h>

#include <xen/interface/xen.h>
@@ -52,6 +54,9 @@ 
#include <xen/hvc-console.h>

#include <xen/swiotlb-xen.h>

#include <xen/balloon.h>

#ifdef CONFIG_X86

#include <asm/xen/cpuid.h>

#endif

#include <asm/xen/hypercall.h>

#include <asm/xen/interface.h>
@@ -68,6 +73,8 @@ static int gnttab_free_count; 
static grant_ref_t gnttab_free_head;

static DEFINE_SPINLOCK(gnttab_list_lock);

struct grant_frames xen_auto_xlat_grant_frames;

static unsigned int xen_gnttab_version;

module_param_named(version, xen_gnttab_version, uint, 0);



static union {

	struct grant_entry_v1 *v1;
@@ -1177,13 +1184,37 @@ static const struct gnttab_ops gnttab_v2_ops = { 
	.query_foreign_access		= gnttab_query_foreign_access_v2,

};



static bool gnttab_need_v2(void)

{

#ifdef CONFIG_X86

	uint32_t base, width;



	if (xen_pv_domain()) {

		base = xen_cpuid_base();

		if (cpuid_eax(base) < 5)

			return false;	/* Information not available, use V1. */

		width = cpuid_ebx(base + 5) &

			XEN_CPUID_MACHINE_ADDRESS_WIDTH_MASK;

		return width > 32 + PAGE_SHIFT;

	}

#endif

	return !!(max_possible_pfn >> 32);

}



static void gnttab_request_version(void)

{

	int rc;

	long rc;

	struct gnttab_set_version gsv;



	if (gnttab_need_v2())

		gsv.version = 2;

	else

		gsv.version = 1;



	/* Boot parameter overrides automatic selection. */

	if (xen_gnttab_version >= 1 && xen_gnttab_version <= 2)

		gsv.version = xen_gnttab_version;



	rc = HYPERVISOR_grant_table_op(GNTTABOP_set_version, &gsv, 1);

	if (rc == 0 && gsv.version == 2)

		gnttab_interface = &gnttab_v2_ops;