Re: [Qemu-devel] [RFC QEMU PATCH v4 02/10] xen-hvm: create the hotplug memory region on Xen

[Haozhong Zhang]

On 02/27/18 16:37 +, Anthony PERARD wrote:
> On Thu, Dec 07, 2017 at 06:18:04PM +0800, Haozhong Zhang wrote:
> > The guest physical address of vNVDIMM is allocated from the hotplug
> > memory region, which is not created when QEMU is used as Xen device
> > model. In order to use vNVDIMM for Xen HVM domains, this commit reuses
> > the code for pc machine type to create the hotplug memory region for
> > Xen HVM domains.
> > 
> > Signed-off-by: Haozhong Zhang 
> > ---
> > Cc: "Michael S. Tsirkin" 
> > Cc: Paolo Bonzini 
> > Cc: Richard Henderson 
> > Cc: Eduardo Habkost 
> > Cc: Stefano Stabellini 
> > Cc: Anthony Perard 
> > ---
> >  hw/i386/pc.c  | 86 
> > ---
> >  hw/i386/xen/xen-hvm.c |  2 ++
> >  include/hw/i386/pc.h  |  1 +
> >  3 files changed, 51 insertions(+), 38 deletions(-)
> > 
> > diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> > index 186545d2a4..9f46c8df79 100644
> > --- a/hw/i386/pc.c
> > +++ b/hw/i386/pc.c
> > @@ -1315,6 +1315,53 @@ void xen_load_linux(PCMachineState *pcms)
> >  pcms->fw_cfg = fw_cfg;
> >  }
> >  
> > +void pc_memory_hotplug_init(PCMachineState *pcms, MemoryRegion 
> > *system_memory)
> 
> It might be better to have a separate patch which move the code into a 
> function.

will move it to a separate patch

> 
> > +{
> > +MachineState *machine = MACHINE(pcms);
> > +PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
> > +ram_addr_t hotplug_mem_size = machine->maxram_size - machine->ram_size;
> > +
> > +if (!pcmc->has_reserved_memory || machine->ram_size >= 
> > machine->maxram_size)
> > +return;
> > +
> > +if (memory_region_size(>hotplug_memory.mr)) {
> 
> This new check looks like to catch programming error, rather than user
> error. Would it be better to be an assert instead?

Well, this was a debugging check and I forgot to remove it before
sending the patch. I'll drop it in the next version.

Thanks,
Haozhong

> 
> > +error_report("hotplug memory region has been initialized");
> > +exit(EXIT_FAILURE);
> > +}
> > +
> 
> -- 
> Anthony PERARD

Re: [Qemu-devel] [RFC QEMU PATCH v4 02/10] xen-hvm: create the hotplug memory region on Xen

[Anthony PERARD]

On Thu, Dec 07, 2017 at 06:18:04PM +0800, Haozhong Zhang wrote:
> The guest physical address of vNVDIMM is allocated from the hotplug
> memory region, which is not created when QEMU is used as Xen device
> model. In order to use vNVDIMM for Xen HVM domains, this commit reuses
> the code for pc machine type to create the hotplug memory region for
> Xen HVM domains.
> 
> Signed-off-by: Haozhong Zhang 
> ---
> Cc: "Michael S. Tsirkin" 
> Cc: Paolo Bonzini 
> Cc: Richard Henderson 
> Cc: Eduardo Habkost 
> Cc: Stefano Stabellini 
> Cc: Anthony Perard 
> ---
>  hw/i386/pc.c  | 86 
> ---
>  hw/i386/xen/xen-hvm.c |  2 ++
>  include/hw/i386/pc.h  |  1 +
>  3 files changed, 51 insertions(+), 38 deletions(-)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 186545d2a4..9f46c8df79 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1315,6 +1315,53 @@ void xen_load_linux(PCMachineState *pcms)
>  pcms->fw_cfg = fw_cfg;
>  }
>  
> +void pc_memory_hotplug_init(PCMachineState *pcms, MemoryRegion 
> *system_memory)

It might be better to have a separate patch which move the code into a function.

> +{
> +MachineState *machine = MACHINE(pcms);
> +PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
> +ram_addr_t hotplug_mem_size = machine->maxram_size - machine->ram_size;
> +
> +if (!pcmc->has_reserved_memory || machine->ram_size >= 
> machine->maxram_size)
> +return;
> +
> +if (memory_region_size(>hotplug_memory.mr)) {

This new check looks like to catch programming error, rather than user
error. Would it be better to be an assert instead?

> +error_report("hotplug memory region has been initialized");
> +exit(EXIT_FAILURE);
> +}
> +

-- 
Anthony PERARD

[Qemu-devel] [RFC QEMU PATCH v4 02/10] xen-hvm: create the hotplug memory region on Xen

[Haozhong Zhang]

The guest physical address of vNVDIMM is allocated from the hotplug
memory region, which is not created when QEMU is used as Xen device
model. In order to use vNVDIMM for Xen HVM domains, this commit reuses
the code for pc machine type to create the hotplug memory region for
Xen HVM domains.

Signed-off-by: Haozhong Zhang 
---
Cc: "Michael S. Tsirkin" 
Cc: Paolo Bonzini 
Cc: Richard Henderson 
Cc: Eduardo Habkost 
Cc: Stefano Stabellini 
Cc: Anthony Perard 
---
 hw/i386/pc.c  | 86 ---
 hw/i386/xen/xen-hvm.c |  2 ++
 include/hw/i386/pc.h  |  1 +
 3 files changed, 51 insertions(+), 38 deletions(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 186545d2a4..9f46c8df79 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1315,6 +1315,53 @@ void xen_load_linux(PCMachineState *pcms)
 pcms->fw_cfg = fw_cfg;
 }
 
+void pc_memory_hotplug_init(PCMachineState *pcms, MemoryRegion *system_memory)
+{
+MachineState *machine = MACHINE(pcms);
+PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
+ram_addr_t hotplug_mem_size = machine->maxram_size - machine->ram_size;
+
+if (!pcmc->has_reserved_memory || machine->ram_size >= 
machine->maxram_size)
+return;
+
+if (memory_region_size(>hotplug_memory.mr)) {
+error_report("hotplug memory region has been initialized");
+exit(EXIT_FAILURE);
+}
+
+if (machine->ram_slots > ACPI_MAX_RAM_SLOTS) {
+error_report("unsupported amount of memory slots: %"PRIu64,
+ machine->ram_slots);
+exit(EXIT_FAILURE);
+}
+
+if (QEMU_ALIGN_UP(machine->maxram_size,
+  TARGET_PAGE_SIZE) != machine->maxram_size) {
+error_report("maximum memory size must by aligned to multiple of "
+ "%d bytes", TARGET_PAGE_SIZE);
+exit(EXIT_FAILURE);
+}
+
+pcms->hotplug_memory.base =
+ROUND_UP(0x1ULL + pcms->above_4g_mem_size, 1ULL << 30);
+
+if (pcmc->enforce_aligned_dimm) {
+/* size hotplug region assuming 1G page max alignment per slot */
+hotplug_mem_size += (1ULL << 30) * machine->ram_slots;
+}
+
+if ((pcms->hotplug_memory.base + hotplug_mem_size) < hotplug_mem_size) {
+error_report("unsupported amount of maximum memory: " RAM_ADDR_FMT,
+ machine->maxram_size);
+exit(EXIT_FAILURE);
+}
+
+memory_region_init(>hotplug_memory.mr, OBJECT(pcms),
+   "hotplug-memory", hotplug_mem_size);
+memory_region_add_subregion(system_memory, pcms->hotplug_memory.base,
+>hotplug_memory.mr);
+}
+
 void pc_memory_init(PCMachineState *pcms,
 MemoryRegion *system_memory,
 MemoryRegion *rom_memory,
@@ -1366,44 +1413,7 @@ void pc_memory_init(PCMachineState *pcms,
 }
 
 /* initialize hotplug memory address space */
-if (pcmc->has_reserved_memory &&
-(machine->ram_size < machine->maxram_size)) {
-ram_addr_t hotplug_mem_size =
-machine->maxram_size - machine->ram_size;
-
-if (machine->ram_slots > ACPI_MAX_RAM_SLOTS) {
-error_report("unsupported amount of memory slots: %"PRIu64,
- machine->ram_slots);
-exit(EXIT_FAILURE);
-}
-
-if (QEMU_ALIGN_UP(machine->maxram_size,
-  TARGET_PAGE_SIZE) != machine->maxram_size) {
-error_report("maximum memory size must by aligned to multiple of "
- "%d bytes", TARGET_PAGE_SIZE);
-exit(EXIT_FAILURE);
-}
-
-pcms->hotplug_memory.base =
-ROUND_UP(0x1ULL + pcms->above_4g_mem_size, 1ULL << 30);
-
-if (pcmc->enforce_aligned_dimm) {
-/* size hotplug region assuming 1G page max alignment per slot */
-hotplug_mem_size += (1ULL << 30) * machine->ram_slots;
-}
-
-if ((pcms->hotplug_memory.base + hotplug_mem_size) <
-hotplug_mem_size) {
-error_report("unsupported amount of maximum memory: " RAM_ADDR_FMT,
- machine->maxram_size);
-exit(EXIT_FAILURE);
-}
-
-memory_region_init(>hotplug_memory.mr, OBJECT(pcms),
-   "hotplug-memory", hotplug_mem_size);
-memory_region_add_subregion(system_memory, pcms->hotplug_memory.base,
->hotplug_memory.mr);
-}
+pc_memory_hotplug_init(pcms, system_memory);
 
 /* Initialize PC system firmware */
 pc_system_firmware_init(rom_memory, !pcmc->pci_enabled);
diff --git a/hw/i386/xen/xen-hvm.c b/hw/i386/xen/xen-hvm.c
index 02d92fd268..fe01b7a025 100644
--- a/hw/i386/xen/xen-hvm.c
+++ b/hw/i386/xen/xen-hvm.c
@@ -235,6 +235,8 @@ static void