[PATCH 0/3] xen: use X86_FEATURE_XENPV for PV specific code

[PATCH 0/3] xen: use X86_FEATURE_XENPV for PV specific code

[Juergen Gross]

Instead of using a global variable with the current guest type or the
XENFEAT_auto_translated_physmap Xen feature, use the already existing
X86_FEATURE_XENPV for guarding PV mode specific code.

This has the advantage of compile time code elimination in case of the
kernel having been configured without CONFIG_XEN_PV, and the usage of
static-keys for selecting the correct code path otherwise.

Juergen Gross (3):
  xen: rework xen_pv_domain()
  xen: replace XENFEAT_auto_translated_physmap with xen_pv_domain()
  drivers/xen/gntdev: use xen_pv_domain() instead of cached value

 arch/x86/include/asm/xen/page.h    | 14 ++++++-------
 arch/x86/xen/enlighten_pv.c        |  2 +-
 arch/x86/xen/mmu.c                 |  2 +-
 arch/x86/xen/p2m.c                 |  4 ++--
 drivers/xen/balloon.c              |  4 ++--
 drivers/xen/gntdev-dmabuf.c        |  7 +++----
 drivers/xen/gntdev-dmabuf.h        |  2 +-
 drivers/xen/gntdev.c               | 33 +++++++++++++-----------------
 drivers/xen/grant-table.c          |  6 +++---
 drivers/xen/privcmd.c              | 14 ++++++-------
 drivers/xen/unpopulated-alloc.c    |  4 ++--
 drivers/xen/xenbus/xenbus_client.c |  2 +-
 include/xen/grant_table.h          |  4 ++--
 include/xen/mem-reservation.h      |  4 ++--
 include/xen/xen-ops.h              |  7 ++++---
 include/xen/xen.h                  |  9 +++++++-
 16 files changed, 59 insertions(+), 59 deletions(-)

-- 
2.43.0

[PATCH 1/3] xen: rework xen_pv_domain()

[Juergen Gross]

Rework xen_pv_domain() to no longer use the xen_domain_type variable,
but the artificial X86_FEATURE_XENPV cpu feature.

On non-x86 architectures xen_pv_domain() can be defined as "0".

This has the advantage that a kernel not built with CONFIG_XEN_PV
will be smaller due to dead code elimination.

Set the X86_FEATURE_XENPV feature very early, as xen_pv_domain() is
used rather early, too.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 arch/x86/xen/enlighten_pv.c | 2 +-
 include/xen/xen.h           | 9 ++++++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 26bbaf4b7330..4806cc28d7ca 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -382,7 +382,6 @@ static bool __init xen_check_xsave(void)
 
 static void __init xen_init_capabilities(void)
 {
-	setup_force_cpu_cap(X86_FEATURE_XENPV);
 	setup_clear_cpu_cap(X86_FEATURE_DCA);
 	setup_clear_cpu_cap(X86_FEATURE_APERFMPERF);
 	setup_clear_cpu_cap(X86_FEATURE_MTRR);
@@ -1402,6 +1401,7 @@ asmlinkage __visible void __init xen_start_kernel(struct start_info *si)
 			JMP32_INSN_SIZE);
 
 	xen_domain_type = XEN_PV_DOMAIN;
+	setup_force_cpu_cap(X86_FEATURE_XENPV);
 	xen_start_flags = xen_start_info->flags;
 	/* Interrupts are guaranteed to be off initially. */
 	early_boot_irqs_disabled = true;
diff --git a/include/xen/xen.h b/include/xen/xen.h
index a1e5b3f18d69..61854e3f2837 100644
--- a/include/xen/xen.h
+++ b/include/xen/xen.h
@@ -22,8 +22,15 @@ extern bool xen_pvh;
 #define xen_pvh			0
 #endif
 
+#ifdef CONFIG_X86
+#include <asm/cpufeature.h>
+
+#define xen_pv_domain()		(cpu_feature_enabled(X86_FEATURE_XENPV))
+#else
+#define xen_pv_domain()		0
+#endif
+
 #define xen_domain()		(xen_domain_type != XEN_NATIVE)
-#define xen_pv_domain()		(xen_domain_type == XEN_PV_DOMAIN)
 #define xen_hvm_domain()	(xen_domain_type == XEN_HVM_DOMAIN)
 #define xen_pvh_domain()	(xen_pvh)
 
-- 
2.43.0

[PATCH 2/3] xen: replace XENFEAT_auto_translated_physmap with xen_pv_domain()

[Juergen Gross]

Instead of testing the XENFEAT_auto_translated_physmap feature, just
use !xen_pv_domain() which is equivalent.

This has the advantage that a kernel not built with CONFIG_XEN_PV
will be smaller due to dead code elimination.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 arch/x86/include/asm/xen/page.h    | 14 +++++++-------
 arch/x86/xen/mmu.c                 |  2 +-
 arch/x86/xen/p2m.c                 |  4 ++--
 drivers/xen/balloon.c              |  4 ++--
 drivers/xen/gntdev.c               |  2 +-
 drivers/xen/grant-table.c          |  6 +++---
 drivers/xen/privcmd.c              | 14 ++++++--------
 drivers/xen/unpopulated-alloc.c    |  4 ++--
 drivers/xen/xenbus/xenbus_client.c |  2 +-
 include/xen/grant_table.h          |  4 ++--
 include/xen/mem-reservation.h      |  4 ++--
 include/xen/xen-ops.h              |  7 ++++---
 12 files changed, 33 insertions(+), 34 deletions(-)

diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index 85e63d58c074..59f642a94b9d 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -12,9 +12,9 @@
 #include <asm/extable.h>
 #include <asm/page.h>
 
+#include <xen/xen.h>
 #include <xen/interface/xen.h>
 #include <xen/interface/grant_table.h>
-#include <xen/features.h>
 
 /* Xen machine address */
 typedef struct xmaddr {
@@ -162,7 +162,7 @@ static inline unsigned long pfn_to_mfn(unsigned long pfn)
 	 * pfn_to_mfn. This will have to be removed when we figured
 	 * out which call.
 	 */
-	if (xen_feature(XENFEAT_auto_translated_physmap))
+	if (!xen_pv_domain())
 		return pfn;
 
 	mfn = __pfn_to_mfn(pfn);
@@ -175,7 +175,7 @@ static inline unsigned long pfn_to_mfn(unsigned long pfn)
 
 static inline int phys_to_machine_mapping_valid(unsigned long pfn)
 {
-	if (xen_feature(XENFEAT_auto_translated_physmap))
+	if (!xen_pv_domain())
 		return 1;
 
 	return __pfn_to_mfn(pfn) != INVALID_P2M_ENTRY;
@@ -210,7 +210,7 @@ static inline unsigned long mfn_to_pfn(unsigned long mfn)
 	 * gfn_to_pfn. This will have to be removed when we figure
 	 * out which call.
 	 */
-	if (xen_feature(XENFEAT_auto_translated_physmap))
+	if (!xen_pv_domain())
 		return mfn;
 
 	pfn = mfn_to_pfn_no_overrides(mfn);
@@ -242,7 +242,7 @@ static inline xpaddr_t machine_to_phys(xmaddr_t machine)
 /* Pseudo-physical <-> Guest conversion */
 static inline unsigned long pfn_to_gfn(unsigned long pfn)
 {
-	if (xen_feature(XENFEAT_auto_translated_physmap))
+	if (!xen_pv_domain())
 		return pfn;
 	else
 		return pfn_to_mfn(pfn);
@@ -250,7 +250,7 @@ static inline unsigned long pfn_to_gfn(unsigned long pfn)
 
 static inline unsigned long gfn_to_pfn(unsigned long gfn)
 {
-	if (xen_feature(XENFEAT_auto_translated_physmap))
+	if (!xen_pv_domain())
 		return gfn;
 	else
 		return mfn_to_pfn(gfn);
@@ -284,7 +284,7 @@ static inline unsigned long bfn_to_local_pfn(unsigned long mfn)
 {
 	unsigned long pfn;
 
-	if (xen_feature(XENFEAT_auto_translated_physmap))
+	if (!xen_pv_domain())
 		return mfn;
 
 	pfn = mfn_to_pfn(mfn);
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index c4c479373249..3be45bf4bc79 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -41,7 +41,7 @@ EXPORT_SYMBOL_GPL(arbitrary_virt_to_machine);
 int xen_unmap_domain_gfn_range(struct vm_area_struct *vma,
 			       int nr, struct page **pages)
 {
-	if (xen_feature(XENFEAT_auto_translated_physmap))
+	if (!xen_pv_domain())
 		return xen_xlate_unmap_gfn_range(vma, nr, pages);
 
 	if (!pages)
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 56914e21e303..2dd12b61a230 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -686,7 +686,7 @@ int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
 	int i, ret = 0;
 	pte_t *pte;
 
-	if (xen_feature(XENFEAT_auto_translated_physmap))
+	if (!xen_pv_domain())
 		return 0;
 
 	if (kmap_ops) {
@@ -769,7 +769,7 @@ int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
 {
 	int i, ret = 0;
 
-	if (xen_feature(XENFEAT_auto_translated_physmap))
+	if (!xen_pv_domain())
 		return 0;
 
 	for (i = 0; i < count; i++) {
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 2de37dcd7556..49c3f9926394 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -302,7 +302,7 @@ static enum bp_state reserve_additional_memory(void)
          * are not restored since this region is now known not to
          * conflict with any devices.
          */ 
-	if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+	if (xen_pv_domain()) {
 		unsigned long pfn, i;
 
 		pfn = PFN_DOWN(resource->start);
@@ -626,7 +626,7 @@ int xen_alloc_ballooned_pages(unsigned int nr_pages, struct page **pages)
 			 */
 			BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE);
 
-			if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+			if (xen_pv_domain()) {
 				ret = xen_alloc_p2m_entry(page_to_pfn(page));
 				if (ret < 0)
 					goto out_undo;
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 1f2160765618..74491967f2ae 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -1183,7 +1183,7 @@ static int __init gntdev_init(void)
 	if (!xen_domain())
 		return -ENODEV;
 
-	use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap);
+	use_ptemod = xen_pv_domain();
 
 	err = misc_register(&gntdev_miscdev);
 	if (err != 0) {
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 04a6b470b15d..478d2ad725ac 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -1449,7 +1449,7 @@ static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
 	unsigned int nr_gframes = end_idx + 1;
 	int rc;
 
-	if (xen_feature(XENFEAT_auto_translated_physmap)) {
+	if (!xen_pv_domain()) {
 		struct xen_add_to_physmap xatp;
 		unsigned int i = end_idx;
 		rc = 0;
@@ -1570,7 +1570,7 @@ static int gnttab_setup(void)
 	if (max_nr_gframes < nr_grant_frames)
 		return -ENOSYS;
 
-	if (xen_feature(XENFEAT_auto_translated_physmap) && gnttab_shared.addr == NULL) {
+	if (!xen_pv_domain() && gnttab_shared.addr == NULL) {
 		gnttab_shared.addr = xen_auto_xlat_grant_frames.vaddr;
 		if (gnttab_shared.addr == NULL) {
 			pr_warn("gnttab share frames is not mapped!\n");
@@ -1588,7 +1588,7 @@ int gnttab_resume(void)
 
 int gnttab_suspend(void)
 {
-	if (!xen_feature(XENFEAT_auto_translated_physmap))
+	if (xen_pv_domain())
 		gnttab_interface->unmap_frames();
 	return 0;
 }
diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index 13a10f3294a8..f52a457b302d 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -271,7 +271,7 @@ static long privcmd_ioctl_mmap(struct file *file, void __user *udata)
 	struct mmap_gfn_state state;
 
 	/* We only support privcmd_ioctl_mmap_batch for non-auto-translated. */
-	if (xen_feature(XENFEAT_auto_translated_physmap))
+	if (!xen_pv_domain())
 		return -ENOSYS;
 
 	if (copy_from_user(&mmapcmd, udata, sizeof(mmapcmd)))
@@ -353,7 +353,7 @@ static int mmap_batch_fn(void *data, int nr, void *state)
 	struct page **cur_pages = NULL;
 	int ret;
 
-	if (xen_feature(XENFEAT_auto_translated_physmap))
+	if (!xen_pv_domain())
 		cur_pages = &pages[st->index];
 
 	BUG_ON(nr < 0);
@@ -535,7 +535,7 @@ static long privcmd_ioctl_mmap_batch(
 			ret = -EINVAL;
 			goto out_unlock;
 		}
-		if (xen_feature(XENFEAT_auto_translated_physmap)) {
+		if (!xen_pv_domain()) {
 			ret = alloc_empty_pages(vma, nr_pages);
 			if (ret < 0)
 				goto out_unlock;
@@ -779,8 +779,7 @@ static long privcmd_ioctl_mmap_resource(struct file *file,
 		goto out;
 	}
 
-	if (IS_ENABLED(CONFIG_XEN_AUTO_XLATE) &&
-	    xen_feature(XENFEAT_auto_translated_physmap)) {
+	if (IS_ENABLED(CONFIG_XEN_AUTO_XLATE) && !xen_pv_domain()) {
 		unsigned int nr = DIV_ROUND_UP(kdata.num, XEN_PFN_PER_PAGE);
 		struct page **pages;
 		unsigned int i;
@@ -811,8 +810,7 @@ static long privcmd_ioctl_mmap_resource(struct file *file,
 	if (rc)
 		goto out;
 
-	if (IS_ENABLED(CONFIG_XEN_AUTO_XLATE) &&
-	    xen_feature(XENFEAT_auto_translated_physmap)) {
+	if (IS_ENABLED(CONFIG_XEN_AUTO_XLATE) && !xen_pv_domain()) {
 		rc = xen_remap_vma_range(vma, kdata.addr, kdata.num << PAGE_SHIFT);
 	} else {
 		unsigned int domid =
@@ -1591,7 +1589,7 @@ static void privcmd_close(struct vm_area_struct *vma)
 	int numgfns = (vma->vm_end - vma->vm_start) >> XEN_PAGE_SHIFT;
 	int rc;
 
-	if (!xen_feature(XENFEAT_auto_translated_physmap) || !numpgs || !pages)
+	if (xen_pv_domain() || !numpgs || !pages)
 		return;
 
 	rc = xen_unmap_domain_gfn_range(vma, numgfns, pages);
diff --git a/drivers/xen/unpopulated-alloc.c b/drivers/xen/unpopulated-alloc.c
index a39f2d36dd9c..d6fc2aefe264 100644
--- a/drivers/xen/unpopulated-alloc.c
+++ b/drivers/xen/unpopulated-alloc.c
@@ -105,7 +105,7 @@ static int fill_list(unsigned int nr_pages)
          * are not restored since this region is now known not to
          * conflict with any devices.
          */
-	if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+	if (xen_pv_domain()) {
 		xen_pfn_t pfn = PFN_DOWN(res->start);
 
 		for (i = 0; i < alloc_pages; i++) {
@@ -184,7 +184,7 @@ int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages)
 		pages[i] = pg;
 
 #ifdef CONFIG_XEN_HAVE_PVMMU
-		if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+		if (xen_pv_domain()) {
 			ret = xen_alloc_p2m_entry(page_to_pfn(pg));
 			if (ret < 0) {
 				unsigned int j;
diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index e73ec225d4a6..2dc874fb5506 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -955,7 +955,7 @@ static const struct xenbus_ring_ops ring_ops_hvm = {
 void __init xenbus_ring_ops_init(void)
 {
 #ifdef CONFIG_XEN_PV
-	if (!xen_feature(XENFEAT_auto_translated_physmap))
+	if (xen_pv_domain())
 		ring_ops = &ring_ops_pv;
 	else
 #endif
diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
index e279be353e3f..69ac6d80a006 100644
--- a/include/xen/grant_table.h
+++ b/include/xen/grant_table.h
@@ -164,7 +164,7 @@ gnttab_set_map_op(struct gnttab_map_grant_ref *map, phys_addr_t addr,
 {
 	if (flags & GNTMAP_contains_pte)
 		map->host_addr = addr;
-	else if (xen_feature(XENFEAT_auto_translated_physmap))
+	else if (!xen_pv_domain())
 		map->host_addr = __pa(addr);
 	else
 		map->host_addr = addr;
@@ -181,7 +181,7 @@ gnttab_set_unmap_op(struct gnttab_unmap_grant_ref *unmap, phys_addr_t addr,
 {
 	if (flags & GNTMAP_contains_pte)
 		unmap->host_addr = addr;
-	else if (xen_feature(XENFEAT_auto_translated_physmap))
+	else if (!xen_pv_domain())
 		unmap->host_addr = __pa(addr);
 	else
 		unmap->host_addr = addr;
diff --git a/include/xen/mem-reservation.h b/include/xen/mem-reservation.h
index a2ab516fcd2c..3cbe3df0dfd4 100644
--- a/include/xen/mem-reservation.h
+++ b/include/xen/mem-reservation.h
@@ -39,7 +39,7 @@ static inline void xenmem_reservation_va_mapping_update(unsigned long count,
 							xen_pfn_t *frames)
 {
 #ifdef CONFIG_XEN_HAVE_PVMMU
-	if (!xen_feature(XENFEAT_auto_translated_physmap))
+	if (xen_pv_domain())
 		__xenmem_reservation_va_mapping_update(count, pages, frames);
 #endif
 }
@@ -48,7 +48,7 @@ static inline void xenmem_reservation_va_mapping_reset(unsigned long count,
 						       struct page **pages)
 {
 #ifdef CONFIG_XEN_HAVE_PVMMU
-	if (!xen_feature(XENFEAT_auto_translated_physmap))
+	if (xen_pv_domain())
 		__xenmem_reservation_va_mapping_reset(count, pages);
 #endif
 }
diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
index 9e2a769b0d96..496e6013c689 100644
--- a/include/xen/xen-ops.h
+++ b/include/xen/xen-ops.h
@@ -6,6 +6,7 @@
 #include <linux/notifier.h>
 #include <linux/efi.h>
 #include <linux/virtio_anchor.h>
+#include <xen/xen.h>
 #include <xen/features.h>
 #include <asm/xen/interface.h>
 #include <xen/interface/vcpu.h>
@@ -116,7 +117,7 @@ static inline int xen_remap_domain_gfn_array(struct vm_area_struct *vma,
 					     unsigned int domid,
 					     struct page **pages)
 {
-	if (xen_feature(XENFEAT_auto_translated_physmap))
+	if (!xen_pv_domain())
 		return xen_xlate_remap_gfn_array(vma, addr, gfn, nr, err_ptr,
 						 prot, domid, pages);
 
@@ -150,7 +151,7 @@ static inline int xen_remap_domain_mfn_array(struct vm_area_struct *vma,
 					     int nr, int *err_ptr,
 					     pgprot_t prot, unsigned int domid)
 {
-	if (xen_feature(XENFEAT_auto_translated_physmap))
+	if (!xen_pv_domain())
 		return -EOPNOTSUPP;
 
 	return xen_remap_pfn(vma, addr, mfn, nr, err_ptr, prot, domid,
@@ -175,7 +176,7 @@ static inline int xen_remap_domain_gfn_range(struct vm_area_struct *vma,
 					     pgprot_t prot, unsigned int domid,
 					     struct page **pages)
 {
-	if (xen_feature(XENFEAT_auto_translated_physmap))
+	if (!xen_pv_domain())
 		return -EOPNOTSUPP;
 
 	return xen_remap_pfn(vma, addr, &gfn, nr, NULL, prot, domid, false);
-- 
2.43.0

[PATCH 3/3] drivers/xen/gntdev: use xen_pv_domain() instead of cached value

[Juergen Gross]

Eliminate the use_ptemod variable by replacing its use cases with
xen_pv_domain().

Instead of passing the xen_pv_domain() return value to
gntdev_ioctl_dmabuf_exp_from_refs(), use xen_pv_domain() in that
function.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/xen/gntdev-dmabuf.c |  7 +++----
 drivers/xen/gntdev-dmabuf.h |  2 +-
 drivers/xen/gntdev.c        | 33 ++++++++++++++-------------------
 3 files changed, 18 insertions(+), 24 deletions(-)

diff --git a/drivers/xen/gntdev-dmabuf.c b/drivers/xen/gntdev-dmabuf.c
index 82855105ab85..550980dd3b0b 100644
--- a/drivers/xen/gntdev-dmabuf.c
+++ b/drivers/xen/gntdev-dmabuf.c
@@ -720,16 +720,15 @@ static void dmabuf_imp_release_all(struct gntdev_dmabuf_priv *priv)
 
 /* DMA buffer IOCTL support. */
 
-long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv, int use_ptemod,
+long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv,
 				       struct ioctl_gntdev_dmabuf_exp_from_refs __user *u)
 {
 	struct ioctl_gntdev_dmabuf_exp_from_refs op;
 	u32 *refs;
 	long ret;
 
-	if (use_ptemod) {
-		pr_debug("Cannot provide dma-buf: use_ptemode %d\n",
-			 use_ptemod);
+	if (xen_pv_domain()) {
+		pr_debug("Cannot provide dma-buf in a PV domain\n");
 		return -EINVAL;
 	}
 
diff --git a/drivers/xen/gntdev-dmabuf.h b/drivers/xen/gntdev-dmabuf.h
index 3d9b9cf9d5a1..9adf96ac74d3 100644
--- a/drivers/xen/gntdev-dmabuf.h
+++ b/drivers/xen/gntdev-dmabuf.h
@@ -18,7 +18,7 @@ struct gntdev_dmabuf_priv *gntdev_dmabuf_init(struct file *filp);
 
 void gntdev_dmabuf_fini(struct gntdev_dmabuf_priv *priv);
 
-long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv, int use_ptemod,
+long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv,
 				       struct ioctl_gntdev_dmabuf_exp_from_refs __user *u);
 
 long gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 74491967f2ae..91ba5078c9d9 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -73,9 +73,6 @@ module_param(limit, uint, 0644);
 MODULE_PARM_DESC(limit,
 	"Maximum number of grants that may be mapped by one mapping request");
 
-/* True in PV mode, false otherwise */
-static int use_ptemod;
-
 static void unmap_grant_pages(struct gntdev_grant_map *map,
 			      int offset, int pages);
 
@@ -163,7 +160,7 @@ struct gntdev_grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count,
 	    NULL == add->pages     ||
 	    NULL == add->being_removed)
 		goto err;
-	if (use_ptemod) {
+	if (xen_pv_domain()) {
 		add->kmap_ops   = kvmalloc_array(count, sizeof(add->kmap_ops[0]),
 						 GFP_KERNEL);
 		add->kunmap_ops = kvmalloc_array(count, sizeof(add->kunmap_ops[0]),
@@ -211,7 +208,7 @@ struct gntdev_grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count,
 		add->grants[i].ref = INVALID_GRANT_REF;
 		add->map_ops[i].handle = INVALID_GRANT_HANDLE;
 		add->unmap_ops[i].handle = INVALID_GRANT_HANDLE;
-		if (use_ptemod) {
+		if (xen_pv_domain()) {
 			add->kmap_ops[i].handle = INVALID_GRANT_HANDLE;
 			add->kunmap_ops[i].handle = INVALID_GRANT_HANDLE;
 		}
@@ -268,7 +265,7 @@ void gntdev_put_map(struct gntdev_priv *priv, struct gntdev_grant_map *map)
 	if (!refcount_dec_and_test(&map->users))
 		return;
 
-	if (map->pages && !use_ptemod) {
+	if (map->pages && !xen_pv_domain()) {
 		/*
 		 * Increment the reference count.  This ensures that the
 		 * subsequent call to unmap_grant_pages() will not wind up
@@ -298,7 +295,7 @@ void gntdev_put_map(struct gntdev_priv *priv, struct gntdev_grant_map *map)
 		 */
 	}
 
-	if (use_ptemod && map->notifier_init)
+	if (xen_pv_domain() && map->notifier_init)
 		mmu_interval_notifier_remove(&map->notifier);
 
 	if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
@@ -334,7 +331,7 @@ int gntdev_map_grant_pages(struct gntdev_grant_map *map)
 	size_t alloced = 0;
 	int i, err = 0;
 
-	if (!use_ptemod) {
+	if (!xen_pv_domain()) {
 		/* Note: it could already be mapped */
 		if (map->map_ops[0].handle != INVALID_GRANT_HANDLE)
 			return 0;
@@ -389,7 +386,7 @@ int gntdev_map_grant_pages(struct gntdev_grant_map *map)
 		if (map->flags & GNTMAP_device_map)
 			map->unmap_ops[i].dev_bus_addr = map->map_ops[i].dev_bus_addr;
 
-		if (use_ptemod) {
+		if (xen_pv_domain()) {
 			if (map->kmap_ops[i].status == GNTST_okay) {
 				alloced++;
 				map->kunmap_ops[i].handle = map->kmap_ops[i].handle;
@@ -421,7 +418,7 @@ static void __unmap_grant_pages_done(int result,
 			map->unmap_ops[offset+i].handle,
 			map->unmap_ops[offset+i].status);
 		map->unmap_ops[offset+i].handle = INVALID_GRANT_HANDLE;
-		if (use_ptemod) {
+		if (xen_pv_domain()) {
 			if (map->kunmap_ops[offset + i].status == GNTST_okay &&
 			    map->kunmap_ops[offset + i].handle != INVALID_GRANT_HANDLE)
 				successful_unmaps++;
@@ -464,7 +461,7 @@ static void __unmap_grant_pages(struct gntdev_grant_map *map, int offset,
 	}
 
 	map->unmap_data.unmap_ops = map->unmap_ops + offset;
-	map->unmap_data.kunmap_ops = use_ptemod ? map->kunmap_ops + offset : NULL;
+	map->unmap_data.kunmap_ops = xen_pv_domain() ? map->kunmap_ops + offset : NULL;
 	map->unmap_data.pages = map->pages + offset;
 	map->unmap_data.count = pages;
 	map->unmap_data.done = __unmap_grant_pages_done;
@@ -1039,7 +1036,7 @@ static long gntdev_ioctl(struct file *flip,
 
 #ifdef CONFIG_XEN_GNTDEV_DMABUF
 	case IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS:
-		return gntdev_ioctl_dmabuf_exp_from_refs(priv, use_ptemod, ptr);
+		return gntdev_ioctl_dmabuf_exp_from_refs(priv, ptr);
 
 	case IOCTL_GNTDEV_DMABUF_EXP_WAIT_RELEASED:
 		return gntdev_ioctl_dmabuf_exp_wait_released(priv, ptr);
@@ -1086,7 +1083,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 
 	vm_flags_set(vma, VM_DONTEXPAND | VM_DONTDUMP | VM_MIXEDMAP);
 
-	if (use_ptemod)
+	if (xen_pv_domain())
 		vm_flags_set(vma, VM_DONTCOPY);
 
 	vma->vm_private_data = map;
@@ -1102,7 +1099,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 
 	map->pages_vm_start = vma->vm_start;
 
-	if (use_ptemod) {
+	if (xen_pv_domain()) {
 		err = mmu_interval_notifier_insert_locked(
 			&map->notifier, vma->vm_mm, vma->vm_start,
 			vma->vm_end - vma->vm_start, &gntdev_mmu_ops);
@@ -1113,7 +1110,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 	}
 	mutex_unlock(&priv->lock);
 
-	if (use_ptemod) {
+	if (xen_pv_domain()) {
 		/*
 		 * gntdev takes the address of the PTE in find_grant_ptes() and
 		 * passes it to the hypervisor in gntdev_map_grant_pages(). The
@@ -1139,7 +1136,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 	if (err)
 		goto out_put_map;
 
-	if (!use_ptemod) {
+	if (!xen_pv_domain()) {
 		err = vm_map_pages_zero(vma, map->pages, map->count);
 		if (err)
 			goto out_put_map;
@@ -1154,7 +1151,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 out_unlock_put:
 	mutex_unlock(&priv->lock);
 out_put_map:
-	if (use_ptemod)
+	if (xen_pv_domain())
 		unmap_grant_pages(map, 0, map->count);
 	gntdev_put_map(priv, map);
 	return err;
@@ -1183,8 +1180,6 @@ static int __init gntdev_init(void)
 	if (!xen_domain())
 		return -ENODEV;
 
-	use_ptemod = xen_pv_domain();
-
 	err = misc_register(&gntdev_miscdev);
 	if (err != 0) {
 		pr_err("Could not register gntdev device\n");
-- 
2.43.0

Re: [PATCH 1/3] xen: rework xen_pv_domain()

[Jason Andryuk]

On 2025-08-26 10:56, Juergen Gross wrote:
> Rework xen_pv_domain() to no longer use the xen_domain_type variable,
> but the artificial X86_FEATURE_XENPV cpu feature.
> 
> On non-x86 architectures xen_pv_domain() can be defined as "0".
> 
> This has the advantage that a kernel not built with CONFIG_XEN_PV
> will be smaller due to dead code elimination.
> 
> Set the X86_FEATURE_XENPV feature very early, as xen_pv_domain() is
> used rather early, too.
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>

Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>

Re: [PATCH 2/3] xen: replace XENFEAT_auto_translated_physmap with xen_pv_domain()

[Jason Andryuk]

On 2025-08-26 10:56, Juergen Gross wrote:
> Instead of testing the XENFEAT_auto_translated_physmap feature, just
> use !xen_pv_domain() which is equivalent.
> 
> This has the advantage that a kernel not built with CONFIG_XEN_PV
> will be smaller due to dead code elimination.
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>

Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>

Re: [PATCH 3/3] drivers/xen/gntdev: use xen_pv_domain() instead of cached value

[Jason Andryuk]

On 2025-08-26 10:56, Juergen Gross wrote:
> Eliminate the use_ptemod variable by replacing its use cases with
> xen_pv_domain().
> 
> Instead of passing the xen_pv_domain() return value to
> gntdev_ioctl_dmabuf_exp_from_refs(), use xen_pv_domain() in that
> function.
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>

Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>