x86/hyperv: Create and use Hyper-V page definitions

Define HV_HYP_PAGE_SHIFT, HV_HYP_PAGE_SIZE, and HV_HYP_PAGE_MASK because
the Linux guest page size and hypervisor page size concepts are different,
even though they happen to be the same value on x86.

Also, replace PAGE_SIZE with HV_HYP_PAGE_SIZE.
Signed-off-by: Maya Nakamura <m.maya.nakamura@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lkml.kernel.org/r/e95111629abf65d016e983f72494cbf110ce605f.1562916939.git.m.maya.nakamura@gmail.com

arch/x86/include/asm/hyperv-tlfs.h

@@ -12,6 +12,16 @@
 #include <linux/types.h>
 #include <asm/page.h>
 
+/*
+ * While not explicitly listed in the TLFS, Hyper-V always runs with a page size
+ * of 4096. These definitions are used when communicating with Hyper-V using
+ * guest physical pages and guest physical page addresses, since the guest page
+ * size may not be 4096 on all architectures.
+ */
+#define HV_HYP_PAGE_SHIFT      12
+#define HV_HYP_PAGE_SIZE       BIT(HV_HYP_PAGE_SHIFT)
+#define HV_HYP_PAGE_MASK       (~(HV_HYP_PAGE_SIZE - 1))
+
 /*
  * The below CPUID leaves are present if VersionAndFeatures.HypervisorPresent
  * is set by CPUID(HvCpuIdFunctionVersionAndFeatures).
@@ -847,7 +857,7 @@ union hv_gpa_page_range {
  * count is equal with how many entries of union hv_gpa_page_range can
  * be populated into the input parameter page.
  */
-#define HV_MAX_FLUSH_REP_COUNT ((PAGE_SIZE - 2 * sizeof(u64)) /	\
+#define HV_MAX_FLUSH_REP_COUNT ((HV_HYP_PAGE_SIZE - 2 * sizeof(u64)) /	\
 				sizeof(union hv_gpa_page_range))
 
 struct hv_guest_mapping_flush_list {