[PATCH v2 0/3] x86/realmode: use a dummy trampoline for Xen PV guests

[PATCH v2 0/3] x86/realmode: use a dummy trampoline for Xen PV guests

[Juergen Gross]

A Xen PV guests can't run in realmode, so the realmode trampoline can
omitted.

Changes in V2:
- complete new approach

Juergen Gross (3):
  x86/realmode: test real_mode_header outside of real_mode_size_needed()
  x86/realmode: add trampoline reference structure
  x86/xen: add a dummy trampoline for Xen PV guests

 arch/x86/include/asm/realmode.h | 15 +++++++++++----
 arch/x86/platform/efi/quirks.c  |  3 ++-
 arch/x86/realmode/init.c        | 25 ++++++++++++++++++++-----
 arch/x86/xen/enlighten_pv.c     | 17 +++++++++++++++++
 4 files changed, 50 insertions(+), 10 deletions(-)

-- 
2.35.3

[PATCH v2 1/3] x86/realmode: test real_mode_header outside of real_mode_size_needed()

[Juergen Gross]

Move the test for the realmode trampoline memory having been allocated
already to the callers of real_mode_size_needed(). This allows to use
that function in setup_real_mode() and set_real_mode_permissions(),
too.

While at it change the size calculation to use PAGE_ALIGN() instead of
open coding it.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 arch/x86/include/asm/realmode.h | 5 +----
 arch/x86/platform/efi/quirks.c  | 3 ++-
 arch/x86/realmode/init.c        | 6 +++---
 3 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h
index fd6f6e5b755a..1eb3d4232e81 100644
--- a/arch/x86/include/asm/realmode.h
+++ b/arch/x86/include/asm/realmode.h
@@ -78,10 +78,7 @@ extern unsigned char secondary_startup_64_no_verify[];
 
 static inline size_t real_mode_size_needed(void)
 {
-	if (real_mode_header)
-		return 0;	/* already allocated. */
-
-	return ALIGN(real_mode_blob_end - real_mode_blob, PAGE_SIZE);
+	return PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
 }
 
 static inline void set_real_mode_mem(phys_addr_t mem)
diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index b0b848d6933a..7c18ca720eee 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -445,7 +445,8 @@ void __init efi_free_boot_services(void)
 		 * panicking early.)
 		 */
 		rm_size = real_mode_size_needed();
-		if (rm_size && (start + rm_size) < (1<<20) && size >= rm_size) {
+		if (!real_mode_header && rm_size &&
+		    (start + rm_size) < (1<<20) && size >= rm_size) {
 			set_real_mode_mem(start);
 			start += rm_size;
 			size -= rm_size;
diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
index 41d7669a97ad..37a3658efaa0 100644
--- a/arch/x86/realmode/init.c
+++ b/arch/x86/realmode/init.c
@@ -48,7 +48,7 @@ void __init reserve_real_mode(void)
 	phys_addr_t mem;
 	size_t size = real_mode_size_needed();
 
-	if (!size)
+	if (real_mode_header || !size)
 		return;
 
 	WARN_ON(slab_is_available());
@@ -94,7 +94,7 @@ static void __init setup_real_mode(void)
 	unsigned char *base;
 	unsigned long phys_base;
 	struct trampoline_header *trampoline_header;
-	size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
+	size_t size = real_mode_size_needed();
 #ifdef CONFIG_X86_64
 	u64 *trampoline_pgd;
 	u64 efer;
@@ -182,7 +182,7 @@ static void __init setup_real_mode(void)
 static void __init set_real_mode_permissions(void)
 {
 	unsigned char *base = (unsigned char *) real_mode_header;
-	size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
+	size_t size = real_mode_size_needed();
 
 	size_t ro_size =
 		PAGE_ALIGN(real_mode_header->ro_end) -
-- 
2.35.3