On 3/18/20 12:42 PM, Cornelia Huck wrote: > On Wed, 11 Mar 2020 09:21:40 -0400 > Janosch Frank <fran...@linux.ibm.com> wrote: > >> Ballooning in protected VMs can only be done when the guest shares the >> pages it gives to the host. If pages are not shared, the integrity >> checks will fail once those pages have been altered and are given back >> to the guest. >> >> As we currently do not yet have a solution for this we will continue >> like this: >> >> 1. We block ballooning now in QEMU (with this patch) > > add trailing '.' > >> >> 2. Later we will provide a change to virtio that removes the blocker > > s/Later/Later,/ > >> and adds VIRTIO_F_IOMMU_PLATFORM automatically by QEMU when doing the >> protvirt switch. This is ok as the guest balloon driver will reject to >> work with the IOMMU change > > "This is OK, as the balloon driver in Linux (the only supported guest) > will refuse to work with the IOMMU_PLATFORM feature bit set." > > ? > >> >> 3. Later we can fix the guest balloon driver to accept the IOMMU > > "Later, we can fix the Linux guest balloon driver..." > >> feature bit and correctly exercise sharing and unsharing of balloon >> pages > > again, missing trailing '.'
All nits fixed
>
>>
>> Signed-off-by: Janosch Frank <fran...@linux.ibm.com>
>> Reviewed-by: David Hildenbrand <da...@redhat.com>
>> Reviewed-by: Christian Borntraeger <borntrae...@de.ibm.com>
>> ---
>> hw/s390x/s390-virtio-ccw.c | 5 +++++
>> 1 file changed, 5 insertions(+)
>>
>> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
>> index deb31e060052d279..066e01f303c35671 100644
>> --- a/hw/s390x/s390-virtio-ccw.c
>> +++ b/hw/s390x/s390-virtio-ccw.c
>> @@ -41,6 +41,7 @@
>> #include "hw/qdev-properties.h"
>> #include "hw/s390x/tod.h"
>> #include "sysemu/sysemu.h"
>> +#include "sysemu/balloon.h"
>> #include "hw/s390x/pv.h"
>> #include "migration/blocker.h"
>>
>> @@ -326,6 +327,7 @@ static void s390_machine_unprotect(S390CcwMachineState
>> *ms)
>> ms->pv = false;
>> migrate_del_blocker(pv_mig_blocker);
>> error_free_or_abort(&pv_mig_blocker);
>> + qemu_balloon_inhibit(false);
>> }
>>
>> static int s390_machine_protect(S390CcwMachineState *ms)
>> @@ -333,10 +335,12 @@ static int s390_machine_protect(S390CcwMachineState
>> *ms)
>> Error *local_err = NULL;
>> int rc;
>>
>
> Maybe add a comment?
>
> /*
> * Ballooning on protected VMs needs support in the guest for
> * sharing and unsharing balloon pages. Block ballooning for
> * now, until we have a solution to make at least Linux guests
> * either support it or fail gracefully.
> */
>
>> + qemu_balloon_inhibit(true);
>> error_setg(&pv_mig_blocker,
>> "protected VMs are currently not migrateable.");
>> rc = migrate_add_blocker(pv_mig_blocker, &local_err);
>> if (local_err) {
>> + qemu_balloon_inhibit(false);
>> error_report_err(local_err);
>> error_free_or_abort(&pv_mig_blocker);
>> return rc;
>> @@ -345,6 +349,7 @@ static int s390_machine_protect(S390CcwMachineState *ms)
>> /* Create SE VM */
>> rc = s390_pv_vm_enable();
>> if (rc) {
>> + qemu_balloon_inhibit(false);
>> error_report_err(local_err);
>> migrate_del_blocker(pv_mig_blocker);
>> error_free_or_abort(&pv_mig_blocker);
>
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