2024-03-19 16:45:11

by Nina Schoetterl-Glausch

Subject: [PATCH 2/2] KVM: s390: vsie: Use virt_to_phys for facility control block

In order for SIE to interpretively execute STFLE, it requires the real
or absolute address of a facility-list control block.
Before writing the location into the shadow SIE control block, convert
it from a virtual address.
We currently do not run into this bug because the lower 31 bits are the
same for virtual and physical addresses.

Signed-off-by: Nina Schoetterl-Glausch <[email protected]>
---
arch/s390/kvm/vsie.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 3af3bd20ac7b..da2819112e1d 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -12,6 +12,7 @@
#include <linux/list.h>
#include <linux/bitmap.h>
#include <linux/sched/signal.h>
+#include <linux/io.h>

#include <asm/gmap.h>
#include <asm/mmu_context.h>
@@ -1006,7 +1007,7 @@ static int handle_stfle(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
if (read_guest_real(vcpu, fac, &vsie_page->fac,
stfle_size() * sizeof(u64)))
return set_validity_icpt(scb_s, 0x1090U);
- scb_s->fac = (__u32)(__u64) &vsie_page->fac;
+ scb_s->fac = (u32)virt_to_phys(&vsie_page->fac);
}
return 0;
}
--
2.40.1

2024-03-20 11:35:52

by David Hildenbrand

Subject: Re: [PATCH 2/2] KVM: s390: vsie: Use virt_to_phys for facility control block

On 19.03.24 17:44, Nina Schoetterl-Glausch wrote:
> In order for SIE to interpretively execute STFLE, it requires the real
> or absolute address of a facility-list control block.
> Before writing the location into the shadow SIE control block, convert
> it from a virtual address.
> We currently do not run into this bug because the lower 31 bits are the
> same for virtual and physical addresses.

So it's not a bug (yet) :)

But certainly the right thing to do and more future-proof.

Reviewed-by: David Hildenbrand <[email protected]>

--
Cheers,

David / dhildenb