2023-12-08 18:49:26

by Paolo Bonzini

Subject: [PATCH v2] KVM: guest-memfd: fix unused-function warning

With migration disabled, one function becomes unused:

virt/kvm/guest_memfd.c:262:12: error: 'kvm_gmem_migrate_folio' defined but not used [-Werror=unused-function]
262 | static int kvm_gmem_migrate_folio(struct address_space *mapping,
| ^~~~~~~~~~~~~~~~~~~~~~

Remove the #ifdef around the reference so that fallback_migrate_folio()
is never used. The gmem implementation of the hook is trivial; since
the gmem mapping is unmovable, the pages should not be migrated anyway.

Fixes: a7800aa80ea4 ("KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory")
Reported-by: Arnd Bergmann <[email protected]>
Suggested-by: Sean Christopherson <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
---
virt/kvm/guest_memfd.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
index b99272396119..c2e2371720a9 100644
--- a/virt/kvm/guest_memfd.c
+++ b/virt/kvm/guest_memfd.c
@@ -300,9 +300,7 @@ static int kvm_gmem_error_page(struct address_space *mapping, struct page *page)

static const struct address_space_operations kvm_gmem_aops = {
.dirty_folio = noop_dirty_folio,
-#ifdef CONFIG_MIGRATION
.migrate_folio = kvm_gmem_migrate_folio,
-#endif
.error_remove_page = kvm_gmem_error_page,
};

--
2.39.1

2023-12-08 19:05:01

by Sean Christopherson

Subject: Re: [PATCH v2] KVM: guest-memfd: fix unused-function warning

On Fri, Dec 08, 2023, Paolo Bonzini wrote:
> With migration disabled, one function becomes unused:
>
> virt/kvm/guest_memfd.c:262:12: error: 'kvm_gmem_migrate_folio' defined but not used [-Werror=unused-function]
> 262 | static int kvm_gmem_migrate_folio(struct address_space *mapping,
> | ^~~~~~~~~~~~~~~~~~~~~~
>
> Remove the #ifdef around the reference so that fallback_migrate_folio()
> is never used. The gmem implementation of the hook is trivial; since
> the gmem mapping is unmovable, the pages should not be migrated anyway.
>
> Fixes: a7800aa80ea4 ("KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory")
> Reported-by: Arnd Bergmann <[email protected]>
> Suggested-by: Sean Christopherson <[email protected]>
> Signed-off-by: Paolo Bonzini <[email protected]>
> ---

Reviewed-by: Sean Christopherson <[email protected]>