[RFC PATCH 1/6] KVM: guest_memfd: Add config to show the capability to handle error page

[isaku . yamahata]

From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>

Add config, HAVE_GENERIC_PRIVATE_MEM_HANDLE_ERROR, to indicate kvm arch
can handle gmem error page.

Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
---
 virt/kvm/Kconfig     | 3 +++
 virt/kvm/guest_mem.c | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index 1a48cb530092..624df45baff0 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -112,3 +112,6 @@ config KVM_GENERIC_PRIVATE_MEM
        select KVM_GENERIC_MEMORY_ATTRIBUTES
        select KVM_PRIVATE_MEM
        bool
+
+config HAVE_GENERIC_PRIVATE_MEM_HANDLE_ERROR
+	bool
diff --git a/virt/kvm/guest_mem.c b/virt/kvm/guest_mem.c
index 85903c32163f..35d8f03e7937 100644
--- a/virt/kvm/guest_mem.c
+++ b/virt/kvm/guest_mem.c
@@ -307,6 +307,9 @@ static int kvm_gmem_error_page(struct address_space *mapping, struct page *page)
 	pgoff_t start, end;
 	gfn_t gfn;
 
+	if (!IS_ENABLED(CONFIG_HAVE_GENERIC_PRIVATE_MEM_HANDLE_ERROR))
+		return MF_IGNORED;
+
 	filemap_invalidate_lock_shared(mapping);
 
 	start = page->index;
-- 
2.25.1