[Xen-devel] [PATCH 1/6] xen: balloon: allow PVMMU interfaces to be compiled out

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

The ARM platform has no concept of PVMMU and therefor no
HYPERVISOR_update_va_mapping et al. Allow this code to be compiled out
when not required.

In some similar situations (e.g. P2M) we have defined dummy functions
to avoid this, however I think we can/should draw the line at dummying
out actual hypercalls.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 arch/x86/xen/Kconfig  |    1 +
 drivers/xen/Kconfig   |    3 +++
 drivers/xen/balloon.c |    4 ++++
 3 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
index 9323b8c..6d101a1 100644
--- a/arch/x86/xen/Kconfig
+++ b/arch/x86/xen/Kconfig
@@ -6,6 +6,7 @@ config XEN
        bool "Xen guest support"
        select PARAVIRT
        select PARAVIRT_CLOCK
+       select XEN_HAVE_PVMMU
        depends on X86_64 || (X86_32 && X86_PAE && !X86_VISWS)
        depends on X86_CMPXCHG && X86_TSC
        help
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index d4dffcd..9c00652 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -204,4 +204,7 @@ config XEN_MCE_LOG
          Allow kernel fetching MCE error from Xen platform and
          converting it into Linux mcelog format for mcelog tools
 
+config XEN_HAVE_PVMMU
+       bool
+
 endmenu
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index db3aa34..92449a0 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -360,6 +360,7 @@ static enum bp_state increase_reservation(unsigned long 
nr_pages)
                if (!xen_feature(XENFEAT_auto_translated_physmap))
                        set_phys_to_machine(pfn, frame_list[i]);
 
+#ifdef CONFIG_XEN_HAVE_PVMMU
                /* Link back into the page tables if not highmem. */
                if (xen_pv_domain() && !PageHighMem(page) &&
                    !xen_feature(XENFEAT_auto_translated_physmap)) {
@@ -371,6 +372,7 @@ static enum bp_state increase_reservation(unsigned long 
nr_pages)
                                0);
                        BUG_ON(ret);
                }
+#endif
 
                /* Relinquish the page back to the allocator. */
                ClearPageReserved(page);
@@ -419,6 +421,7 @@ static enum bp_state decrease_reservation(unsigned long 
nr_pages, gfp_t gfp)
 
                scrub_page(page);
 
+#ifdef CONFIG_XEN_HAVE_PVMMU
                if (xen_pv_domain() && !PageHighMem(page)) {
                        if (!xen_feature(XENFEAT_auto_translated_physmap)) {
                                ret = HYPERVISOR_update_va_mapping(
@@ -427,6 +430,7 @@ static enum bp_state decrease_reservation(unsigned long 
nr_pages, gfp_t gfp)
                                BUG_ON(ret);
                        }
                }
+#endif
        }
 
        /* Ensure that ballooned highmem pages don't have kmaps. */
-- 
1.7.2.5


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