[PATCH v2 2/3] xen: split up xen_hvm_init_shared_info()

From: Juergen Gross
Date: Fri Jul 28 2017 - 06:23:29 EST


Instead of calling xen_hvm_init_shared_info() on boot and resume split
it up into a boot time function searching for the pfn to use and a
mapping function doing the hypervisor mapping call.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
arch/x86/xen/enlighten_hvm.c | 45 +++++++++++++++++++++++---------------------
1 file changed, 24 insertions(+), 21 deletions(-)

diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
index 87d791356ea9..d23531f5f17e 100644
--- a/arch/x86/xen/enlighten_hvm.c
+++ b/arch/x86/xen/enlighten_hvm.c
@@ -21,29 +21,9 @@
#include "mmu.h"
#include "smp.h"

-void __ref xen_hvm_init_shared_info(void)
+void xen_hvm_init_shared_info(void)
{
struct xen_add_to_physmap xatp;
- u64 pa;
-
- if (HYPERVISOR_shared_info == &xen_dummy_shared_info) {
- /*
- * Search for a free page starting at 4kB physical address.
- * Low memory is preferred to avoid an EPT large page split up
- * by the mapping.
- * Starting below X86_RESERVE_LOW (usually 64kB) is fine as
- * the BIOS used for HVM guests is well behaved and won't
- * clobber memory other than the first 4kB.
- */
- for (pa = PAGE_SIZE;
- !e820__mapped_all(pa, pa + PAGE_SIZE, E820_TYPE_RAM) ||
- memblock_is_reserved(pa);
- pa += PAGE_SIZE)
- ;
-
- memblock_reserve(pa, PAGE_SIZE);
- HYPERVISOR_shared_info = __va(pa);
- }

xatp.domid = DOMID_SELF;
xatp.idx = 0;
@@ -53,6 +33,28 @@ void __ref xen_hvm_init_shared_info(void)
BUG();
}

+static void __init reserve_shared_info(void)
+{
+ u64 pa;
+
+ /*
+ * Search for a free page starting at 4kB physical address.
+ * Low memory is preferred to avoid an EPT large page split up
+ * by the mapping.
+ * Starting below X86_RESERVE_LOW (usually 64kB) is fine as
+ * the BIOS used for HVM guests is well behaved and won't
+ * clobber memory other than the first 4kB.
+ */
+ for (pa = PAGE_SIZE;
+ !e820__mapped_all(pa, pa + PAGE_SIZE, E820_TYPE_RAM) ||
+ memblock_is_reserved(pa);
+ pa += PAGE_SIZE)
+ ;
+
+ memblock_reserve(pa, PAGE_SIZE);
+ HYPERVISOR_shared_info = __va(pa);
+}
+
static void __init init_hvm_pv_info(void)
{
int major, minor;
@@ -153,6 +155,7 @@ static void __init xen_hvm_guest_init(void)

init_hvm_pv_info();

+ reserve_shared_info();
xen_hvm_init_shared_info();

/*
--
2.12.3