| Message ID | 20220930140150.37463-5-imbrenda@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: s390: pv: implement lazy destroy for reboot | expand |
On 9/30/22 16:01, Claudio Imbrenda wrote: > If the appropriate UV feature bit is set, there is no need to perform > an export before import. > > The misc feature indicates, among other things, that importing a shared > page from a different protected VM will automatically also transfer its > ownership. > > Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com> > Reviewed-by: Nico Boehr <nrb@linux.ibm.com> > Reviewed-by: Janosch Frank <frankja@linux.ibm.com> LGTM Reviewed-by: Steffen Eiden <seiden@linux.ibm.com> > --- > arch/s390/kernel/uv.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c > index f9810d2a267c..9f18a4af9c13 100644 > --- a/arch/s390/kernel/uv.c > +++ b/arch/s390/kernel/uv.c > @@ -255,6 +255,13 @@ static int make_secure_pte(pte_t *ptep, unsigned long addr, > */ > static bool should_export_before_import(struct uv_cb_header *uvcb, struct mm_struct *mm) > { > + /* > + * The misc feature indicates, among other things, that importing a > + * shared page from a different protected VM will automatically also > + * transfer its ownership. > + */ > + if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications)) > + return false; > if (uvcb->cmd == UVC_CMD_UNPIN_PAGE_SHARED) > return false; > return atomic_read(&mm->context.protected_count) > 1;
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c index f9810d2a267c..9f18a4af9c13 100644 --- a/arch/s390/kernel/uv.c +++ b/arch/s390/kernel/uv.c @@ -255,6 +255,13 @@ static int make_secure_pte(pte_t *ptep, unsigned long addr, */ static bool should_export_before_import(struct uv_cb_header *uvcb, struct mm_struct *mm) { + /* + * The misc feature indicates, among other things, that importing a + * shared page from a different protected VM will automatically also + * transfer its ownership. + */ + if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications)) + return false; if (uvcb->cmd == UVC_CMD_UNPIN_PAGE_SHARED) return false; return atomic_read(&mm->context.protected_count) > 1;