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Re: [PATCH v3 1/1] vl/s390x: fixup ram sizes for compat machines
From: |
Igor Mammedov |
Subject: |
Re: [PATCH v3 1/1] vl/s390x: fixup ram sizes for compat machines |
Date: |
Wed, 1 Apr 2020 18:34:56 +0200 |
On Wed, 1 Apr 2020 08:37:54 -0400
Christian Borntraeger <address@hidden> wrote:
> Older QEMU versions did fixup the ram size to match what can be reported
> via sclp. We need to mimic this behaviour for machine types 4.2 and
> older to not fail on inbound migration for memory sizes that do not fit.
> Old machines with proper aligned memory sizes are not affected.
>
> Alignment table:
> VM size (<=) | Alignment
> --------------------------
> 1020M | 1M
> 2040M | 2M
> 4080M | 4M
> 8160M | 8M
> 16320M | 16M
> 32640M | 32M
> 65280M | 64M
> 130560M | 128M
> 261120M | 256M
> 522240M | 512M
> 1044480M | 1G
> 2088960M | 2G
> 4177920M | 4G
> 8355840M | 8G
>
> Suggested action is to replace unaligned -m value with a suitable
> aligned one or if a change to a newer machine type is possible, use a
> machine version >= 5.0.
>
> A future versions might remove the compatibility handling.
>
> For machine types >= 5.0 we can simply use an increment size of 1M and
> use the full range of increment number which allows for all possible
> memory sizes. The old limitation of having a maximum of 1020 increments
> was added for standby memory, which we no longer support. With that we
> can now support even weird memory sizes like 10001234 MB.
>
> As we no longer fixup maxram_size as well, make other users use ram_size
> instead. Keep using maxram_size when setting the maximum ram size in KVM,
> as that will come in handy in the future when supporting memory hotplug
> (in contrast, storage keys and storage attributes for hotplugged memory
> will have to be migrated per RAM block in the future).
>
> Fixes: 3a12fc61af5c ("390x/s390-virtio-ccw: use memdev for RAM")
> Reported-by: Lukáš Doktor <address@hidden>
> Cc: Igor Mammedov <address@hidden>
> Cc: Dr. David Alan Gilbert <address@hidden>
> Signed-off-by: David Hildenbrand <address@hidden>
> Signed-off-by: Christian Borntraeger <address@hidden>
Acked-by: Igor Mammedov <address@hidden>
minor nit below if you have to respin
> ---
> hw/s390x/s390-skeys.c | 2 +-
> hw/s390x/s390-stattrib-kvm.c | 4 ++--
> hw/s390x/s390-virtio-ccw.c | 21 +++++++++++++++++++++
> hw/s390x/sclp.c | 17 +++++------------
> include/hw/boards.h | 7 +++++++
> softmmu/vl.c | 3 +++
> 6 files changed, 39 insertions(+), 15 deletions(-)
>
> diff --git a/hw/s390x/s390-skeys.c b/hw/s390x/s390-skeys.c
> index 5da6e5292f..a9a4ae7b39 100644
> --- a/hw/s390x/s390-skeys.c
> +++ b/hw/s390x/s390-skeys.c
> @@ -176,7 +176,7 @@ static void qemu_s390_skeys_init(Object *obj)
> QEMUS390SKeysState *skeys = QEMU_S390_SKEYS(obj);
> MachineState *machine = MACHINE(qdev_get_machine());
>
> - skeys->key_count = machine->maxram_size / TARGET_PAGE_SIZE;
> + skeys->key_count = machine->ram_size / TARGET_PAGE_SIZE;
> skeys->keydata = g_malloc0(skeys->key_count);
> }
>
> diff --git a/hw/s390x/s390-stattrib-kvm.c b/hw/s390x/s390-stattrib-kvm.c
> index c7e1f35524..f89d8d9d16 100644
> --- a/hw/s390x/s390-stattrib-kvm.c
> +++ b/hw/s390x/s390-stattrib-kvm.c
> @@ -85,7 +85,7 @@ static int kvm_s390_stattrib_set_stattr(S390StAttribState
> *sa,
> {
> KVMS390StAttribState *sas = KVM_S390_STATTRIB(sa);
> MachineState *machine = MACHINE(qdev_get_machine());
> - unsigned long max = machine->maxram_size / TARGET_PAGE_SIZE;
> + unsigned long max = machine->ram_size / TARGET_PAGE_SIZE;
>
> if (start_gfn + count > max) {
> error_report("Out of memory bounds when setting storage attributes");
> @@ -104,7 +104,7 @@ static void
> kvm_s390_stattrib_synchronize(S390StAttribState *sa)
> {
> KVMS390StAttribState *sas = KVM_S390_STATTRIB(sa);
> MachineState *machine = MACHINE(qdev_get_machine());
> - unsigned long max = machine->maxram_size / TARGET_PAGE_SIZE;
> + unsigned long max = machine->ram_size / TARGET_PAGE_SIZE;
> /* We do not need to reach the maximum buffer size allowed */
> unsigned long cx, len = KVM_S390_SKEYS_MAX / 2;
> int r;
> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
> index 3cf19c99f3..61a8a0e693 100644
> --- a/hw/s390x/s390-virtio-ccw.c
> +++ b/hw/s390x/s390-virtio-ccw.c
> @@ -27,6 +27,7 @@
> #include "qemu/ctype.h"
> #include "qemu/error-report.h"
> #include "qemu/option.h"
> +#include "qemu/qemu-print.h"
> #include "s390-pci-bus.h"
> #include "sysemu/reset.h"
> #include "hw/s390x/storage-keys.h"
> @@ -579,6 +580,25 @@ static void s390_nmi(NMIState *n, int cpu_index, Error
> **errp)
> s390_cpu_restart(S390_CPU(cs));
> }
>
> +static ram_addr_t s390_fixup_ram_size(ram_addr_t sz)
> +{
> + /* same logic as in sclp.c */
> + int increment_size = 20;
> + ram_addr_t newsz;
> +
> + while ((sz >> increment_size) > MAX_STORAGE_INCREMENTS) {
> + increment_size++;
> + }
> + newsz = sz >> increment_size << increment_size;
> +
> + if (sz != newsz) {
> + qemu_printf("Ram size %" PRIu64 "MB was fixed up to %" PRIu64
^^^^^^^^
for unaware user it could be confusing as it could be read as 'value was
increased'
s/fixed up/amended/ might be better
> + "MB to match machine restrictions. Consider updating "
> + "the guest definition.i\n", sz / MiB, newsz / MiB);
also it might be better to use size_to_str() to format numbers
> + }
> + return newsz;
> +}
> +
> static void ccw_machine_class_init(ObjectClass *oc, void *data)
> {
> MachineClass *mc = MACHINE_CLASS(oc);
> @@ -808,6 +828,7 @@ static void ccw_machine_4_2_instance_options(MachineState
> *machine)
> static void ccw_machine_4_2_class_options(MachineClass *mc)
> {
> ccw_machine_5_0_class_options(mc);
> + mc->fixup_ram_size = s390_fixup_ram_size;
> compat_props_add(mc->compat_props, hw_compat_4_2, hw_compat_4_2_len);
> }
> DEFINE_CCW_MACHINE(4_2, "4.2", false);
> diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c
> index d8ae207731..ede056b3ef 100644
> --- a/hw/s390x/sclp.c
> +++ b/hw/s390x/sclp.c
> @@ -361,27 +361,20 @@ out:
> static void sclp_memory_init(SCLPDevice *sclp)
> {
> MachineState *machine = MACHINE(qdev_get_machine());
> + MachineClass *machine_class = MACHINE_GET_CLASS(qdev_get_machine());
> ram_addr_t initial_mem = machine->ram_size;
> int increment_size = 20;
>
> /* The storage increment size is a multiple of 1M and is a power of 2.
> - * The number of storage increments must be MAX_STORAGE_INCREMENTS or
> fewer.
> + * For some machine types, the number of storage increments must be
> + * MAX_STORAGE_INCREMENTS or fewer.
> * The variable 'increment_size' is an exponent of 2 that can be
> * used to calculate the size (in bytes) of an increment. */
> - while ((initial_mem >> increment_size) > MAX_STORAGE_INCREMENTS) {
> + while (machine_class->fixup_ram_size != NULL &&
> + (initial_mem >> increment_size) > MAX_STORAGE_INCREMENTS) {
> increment_size++;
> }
> sclp->increment_size = increment_size;
> -
> - /* The core memory area needs to be aligned with the increment size.
> - * In effect, this can cause the user-specified memory size to be rounded
> - * down to align with the nearest increment boundary. */
> - initial_mem = initial_mem >> increment_size << increment_size;
> -
> - machine->ram_size = initial_mem;
> - machine->maxram_size = initial_mem;
> - /* let's propagate the changed ram size into the global variable. */
> - ram_size = initial_mem;
> }
>
> static void sclp_init(Object *obj)
> diff --git a/include/hw/boards.h b/include/hw/boards.h
> index 236d239c19..fd4d62b501 100644
> --- a/include/hw/boards.h
> +++ b/include/hw/boards.h
> @@ -152,6 +152,12 @@ typedef struct {
> * It also will be used as a way to optin into "-m" option support.
> * If it's not set by board, '-m' will be ignored and generic code will
> * not create default RAM MemoryRegion.
> + * @fixup_ram_size:
> + * Amends user provided ram size (with -m option) using machine
> + * specific algorithm. To be used by old machine types for compat
> + * purposes only.
> + * Applies only to default memory backend, i.e., explicit memory backend
> + * wasn't used.
> */
> struct MachineClass {
> /*< private >*/
> @@ -218,6 +224,7 @@ struct MachineClass {
> unsigned cpu_index);
> const CPUArchIdList *(*possible_cpu_arch_ids)(MachineState *machine);
> int64_t (*get_default_cpu_node_id)(const MachineState *ms, int idx);
> + ram_addr_t (*fixup_ram_size)(ram_addr_t size);
> };
>
> /**
> diff --git a/softmmu/vl.c b/softmmu/vl.c
> index 1d33a28340..09f8a1b0a7 100644
> --- a/softmmu/vl.c
> +++ b/softmmu/vl.c
> @@ -2601,6 +2601,9 @@ static bool set_memory_options(uint64_t *ram_slots,
> ram_addr_t *maxram_size,
> }
>
> sz = QEMU_ALIGN_UP(sz, 8192);
> + if (mc->fixup_ram_size) {
> + sz = mc->fixup_ram_size(sz);
> + }
> ram_size = sz;
> if (ram_size != sz) {
> error_report("ram size too large");
Re: [PATCH v3 1/1] vl/s390x: fixup ram sizes for compat machines,
Igor Mammedov <=
Re: [PATCH v3 1/1] vl/s390x: fixup ram sizes for compat machines, Igor Mammedov, 2020/04/02
Re: [PATCH v3 1/1] vl/s390x: fixup ram sizes for compat machines, Christian Borntraeger, 2020/04/02
Re: [PATCH v3 1/1] vl/s390x: fixup ram sizes for compat machines, Igor Mammedov, 2020/04/02
Re: [PATCH v3 1/1] vl/s390x: fixup ram sizes for compat machines, Christian Borntraeger, 2020/04/02
Re: [PATCH v3 1/1] vl/s390x: fixup ram sizes for compat machines, Christian Borntraeger, 2020/04/02