Re: [Qemu-devel] [Qemu-ppc] [RESEND PATCH v10 1/5] hw/ppc/spapr.c: adding pending_dimm_unplugs to sPAPRMachineState

2017-05-21 Thread David Gibson 
On Fri, May 19, 2017 at 08:19:41AM -0300, Daniel Henrique Barboza wrote:
> 
> 
> On 05/19/2017 01:26 AM, David Gibson wrote:
> > On Thu, May 18, 2017 at 06:54:12PM -0300, Daniel Henrique Barboza wrote:
> > > The LMB DRC release callback, spapr_lmb_release(), uses an opaque
> > > parameter, a sPAPRDIMMState struct that stores the current LMBs that
> > > are allocated to a DIMM (nr_lmbs). After each call to this callback,
> > > the nr_lmbs is decremented by one and, when it reaches zero, the callback
> > > proceeds with the qdev calls to hot unplug the LMB.
> > > 
> > > Using drc->detach_cb_opaque is problematic because it can't be migrated in
> > > the future DRC migration work. This patch makes the following changes to
> > > eliminate the usage of this opaque callback inside spapr_lmb_release:
> > > 
> > > - sPAPRDIMMState was moved from spapr.c and added to spapr.h. A new
> > > attribute called 'addr' was added to it. This is used as an unique
> > > identifier to associate a sPAPRDIMMState to a PCDIMM element.
> > > 
> > > - sPAPRMachineState now hosts a new QTAILQ called 'pending_dimm_unplugs'.
> > > This queue of sPAPRDIMMState elements will store the DIMM state of DIMMs
> > > that are currently going under an unplug process.
> > > 
> > > - spapr_lmb_release() will now retrieve the nr_lmbs value by getting the
> > > correspondent sPAPRDIMMState. A helper function called 
> > > spapr_dimm_get_address
> > > was created to fetch the address of a PCDIMM device inside 
> > > spapr_lmb_release.
> > > When nr_lmbs reaches zero and the callback proceeds with the qdev hot 
> > > unplug
> > > calls, the sPAPRDIMMState struct is removed from 
> > > spapr->pending_dimm_unplugs.
> > > 
> > > After these changes, the opaque argument for spapr_lmb_release is now
> > > unused and is passed as NULL inside spapr_del_lmbs. This and the other
> > > opaque arguments can now be safely removed from the code.
> > > 
> > > Signed-off-by: Daniel Henrique Barboza 
> > > ---
> > >   hw/ppc/spapr.c | 57 
> > > +-
> > >   include/hw/ppc/spapr.h |  4 
> > >   2 files changed, 56 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > > index 0980d73..b05abe5 100644
> > > --- a/hw/ppc/spapr.c
> > > +++ b/hw/ppc/spapr.c
> > > @@ -2050,6 +2050,7 @@ static void ppc_spapr_init(MachineState *machine)
> > >   msi_nonbroken = true;
> > >   QLIST_INIT(>phbs);
> > > +QTAILQ_INIT(>pending_dimm_unplugs);
> > >   /* Allocate RMA if necessary */
> > >   rma_alloc_size = kvmppc_alloc_rma();
> > > @@ -2603,20 +2604,63 @@ out:
> > >   error_propagate(errp, local_err);
> > >   }
> > > -typedef struct sPAPRDIMMState {
> > > +struct sPAPRDIMMState {
> > > +uint64_t addr;
> > Since you're not trying to migrate this any more, you can index the
> > list by an actual PCDIMMDevice *, rather than the base address.
> > You're already passing the DeviceState * for the DIMM around, so this
> > will actually remove the address parameter from some functions.
> Good idea.
> 
> > 
> > I think that could actually be done as a preliminary cleanup.  It also
> > probably makes sense to merge spapr_del_lmbs() with
> > spapr_memory_unplug_request(), they're both very small.
> 
> Ok.
> 
> > 
> > 
> > >   uint32_t nr_lmbs;
> > > -} sPAPRDIMMState;
> > > +QTAILQ_ENTRY(sPAPRDIMMState) next;
> > > +};
> > > +
> > > +static sPAPRDIMMState *spapr_pending_dimm_unplugs_find(sPAPRMachineState 
> > > *s,
> > > +   uint64_t addr)
> > > +{
> > > +sPAPRDIMMState *dimm_state = NULL;
> > > +QTAILQ_FOREACH(dimm_state, >pending_dimm_unplugs, next) {
> > > +if (dimm_state->addr == addr) {
> > > +break;
> > > +}
> > > +}
> > > +return dimm_state;
> > > +}
> > > +
> > > +static void spapr_pending_dimm_unplugs_add(sPAPRMachineState *spapr,
> > > +   sPAPRDIMMState *dimm_state)
> > > +{
> > > +g_assert(!spapr_pending_dimm_unplugs_find(spapr, dimm_state->addr));
> > > +QTAILQ_INSERT_HEAD(>pending_dimm_unplugs, dimm_state, next);
> > > +}
> > > +
> > > +static void spapr_pending_dimm_unplugs_remove(sPAPRMachineState *spapr,
> > > +  sPAPRDIMMState *dimm_state)
> > > +{
> > > +QTAILQ_REMOVE(>pending_dimm_unplugs, dimm_state, next);
> > > +g_free(dimm_state);
> > > +}
> > > +
> > > +static uint64_t spapr_dimm_get_address(PCDIMMDevice *dimm)
> > > +{
> > > +Error *local_err = NULL;
> > > +uint64_t addr;
> > > +addr = object_property_get_int(OBJECT(dimm), PC_DIMM_ADDR_PROP,
> > > +   _err);
> > > +if (local_err) {
> > > +error_propagate(_abort, local_err);
> > > +return 0;
> > > +}
> > > +return addr;
> > > +}
> > >   static void spapr_lmb_release(DeviceState *dev, void *opaque)

Re: [Qemu-devel] [Qemu-ppc] [RESEND PATCH v10 1/5] hw/ppc/spapr.c: adding pending_dimm_unplugs to sPAPRMachineState

2017-05-19 Thread Daniel Henrique Barboza 



On 05/19/2017 01:26 AM, David Gibson wrote:

On Thu, May 18, 2017 at 06:54:12PM -0300, Daniel Henrique Barboza wrote:

The LMB DRC release callback, spapr_lmb_release(), uses an opaque
parameter, a sPAPRDIMMState struct that stores the current LMBs that
are allocated to a DIMM (nr_lmbs). After each call to this callback,
the nr_lmbs is decremented by one and, when it reaches zero, the callback
proceeds with the qdev calls to hot unplug the LMB.

Using drc->detach_cb_opaque is problematic because it can't be migrated in
the future DRC migration work. This patch makes the following changes to
eliminate the usage of this opaque callback inside spapr_lmb_release:

- sPAPRDIMMState was moved from spapr.c and added to spapr.h. A new
attribute called 'addr' was added to it. This is used as an unique
identifier to associate a sPAPRDIMMState to a PCDIMM element.

- sPAPRMachineState now hosts a new QTAILQ called 'pending_dimm_unplugs'.
This queue of sPAPRDIMMState elements will store the DIMM state of DIMMs
that are currently going under an unplug process.

- spapr_lmb_release() will now retrieve the nr_lmbs value by getting the
correspondent sPAPRDIMMState. A helper function called spapr_dimm_get_address
was created to fetch the address of a PCDIMM device inside spapr_lmb_release.
When nr_lmbs reaches zero and the callback proceeds with the qdev hot unplug
calls, the sPAPRDIMMState struct is removed from spapr->pending_dimm_unplugs.

After these changes, the opaque argument for spapr_lmb_release is now
unused and is passed as NULL inside spapr_del_lmbs. This and the other
opaque arguments can now be safely removed from the code.

Signed-off-by: Daniel Henrique Barboza 
---
  hw/ppc/spapr.c | 57 +-
  include/hw/ppc/spapr.h |  4 
  2 files changed, 56 insertions(+), 5 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 0980d73..b05abe5 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2050,6 +2050,7 @@ static void ppc_spapr_init(MachineState *machine)
  msi_nonbroken = true;
  
  QLIST_INIT(>phbs);

+QTAILQ_INIT(>pending_dimm_unplugs);
  
  /* Allocate RMA if necessary */

  rma_alloc_size = kvmppc_alloc_rma();
@@ -2603,20 +2604,63 @@ out:
  error_propagate(errp, local_err);
  }
  
-typedef struct sPAPRDIMMState {

+struct sPAPRDIMMState {
+uint64_t addr;

Since you're not trying to migrate this any more, you can index the
list by an actual PCDIMMDevice *, rather than the base address.
You're already passing the DeviceState * for the DIMM around, so this
will actually remove the address parameter from some functions.

Good idea.



I think that could actually be done as a preliminary cleanup.  It also
probably makes sense to merge spapr_del_lmbs() with
spapr_memory_unplug_request(), they're both very small.


Ok.





  uint32_t nr_lmbs;
-} sPAPRDIMMState;
+QTAILQ_ENTRY(sPAPRDIMMState) next;
+};
+
+static sPAPRDIMMState *spapr_pending_dimm_unplugs_find(sPAPRMachineState *s,
+   uint64_t addr)
+{
+sPAPRDIMMState *dimm_state = NULL;
+QTAILQ_FOREACH(dimm_state, >pending_dimm_unplugs, next) {
+if (dimm_state->addr == addr) {
+break;
+}
+}
+return dimm_state;
+}
+
+static void spapr_pending_dimm_unplugs_add(sPAPRMachineState *spapr,
+   sPAPRDIMMState *dimm_state)
+{
+g_assert(!spapr_pending_dimm_unplugs_find(spapr, dimm_state->addr));
+QTAILQ_INSERT_HEAD(>pending_dimm_unplugs, dimm_state, next);
+}
+
+static void spapr_pending_dimm_unplugs_remove(sPAPRMachineState *spapr,
+  sPAPRDIMMState *dimm_state)
+{
+QTAILQ_REMOVE(>pending_dimm_unplugs, dimm_state, next);
+g_free(dimm_state);
+}
+
+static uint64_t spapr_dimm_get_address(PCDIMMDevice *dimm)
+{
+Error *local_err = NULL;
+uint64_t addr;
+addr = object_property_get_int(OBJECT(dimm), PC_DIMM_ADDR_PROP,
+   _err);
+if (local_err) {
+error_propagate(_abort, local_err);
+return 0;
+}
+return addr;
+}
  
  static void spapr_lmb_release(DeviceState *dev, void *opaque)

  {
-sPAPRDIMMState *ds = (sPAPRDIMMState *)opaque;
  HotplugHandler *hotplug_ctrl;
+uint64_t addr = spapr_dimm_get_address(PC_DIMM(dev));
+sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());

I prefer not to access the machine as a global when possible.  I think
it's preferable to pass down the spapr object from above -
unplug_request() itself can get it from hotplug_dev.


I see that we have access to the hotplug_dev (HotplugHandler) in the end of
spapr_lmb_release:

hotplug_ctrl = qdev_get_hotplug_handler(dev);

One alternative would be to move this call up in the function and then
retrieve the machine as unplug_request() does:

hotplug_ctrl =