On 10/12/21 10:35, Claudio Imbrenda wrote:
On Tue, 12 Oct 2021 10:16:26 +0200
Janosch Frank <frankja@xxxxxxxxxxxxx> wrote:
On 9/20/21 15:24, Claudio Imbrenda wrote:
With upcoming patches, normal guests might touch secure pages.
This patch extends the existing exception handler to convert the pages
to non secure also when the exception is triggered by a normal guest.
This can happen for example when a secure guest reboots; the first
stage of a secure guest is non secure, and in general a secure guest
can reboot into non-secure mode.
If the secure memory of the previous boot has not been cleared up
completely yet, a non-secure guest might touch secure memory, which
will need to be handled properly.
Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
---
arch/s390/mm/fault.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index eb68b4f36927..74784581f42d 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -767,6 +767,7 @@ void do_secure_storage_access(struct pt_regs *regs)
struct vm_area_struct *vma;
struct mm_struct *mm;
struct page *page;
+ struct gmap *gmap;
int rc;
/*
@@ -796,6 +797,14 @@ void do_secure_storage_access(struct pt_regs *regs)
}
switch (get_fault_type(regs)) {
+ case GMAP_FAULT:
+ gmap = (struct gmap *)S390_lowcore.gmap;
+ addr = __gmap_translate(gmap, addr);
+ if (IS_ERR_VALUE(addr)) {
+ do_fault_error(regs, VM_ACCESS_FLAGS, VM_FAULT_BADMAP);
+ break;
+ }
+ fallthrough;
This would trigger an export and not a destroy, right?
correct. but this would only happen for leftover secure pages touched
by non-secure guests, before the background thread could clean them up.
I.e. we don't expect to need the destroy speed boost?
case USER_FAULT:
mm = current->mm;
mmap_read_lock(mm);
@@ -824,7 +833,6 @@ void do_secure_storage_access(struct pt_regs *regs)
if (rc)
BUG();
break;
- case GMAP_FAULT:
default:
do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
WARN_ON_ONCE(1);
