Now we have the extended memory map (high IO regions beyond the
scalable RAM) and dynamic IPA range support at KVM/ARM level
we can bump the legacy 255GB initial RAM limit. The actual maximum
RAM size now depends on the physical CPU and host kernel, in
accelerated mode. In TCG mode, it depends on the VCPU
AA64MMFR0.PARANGE.

Signed-off-by: Eric Auger <eric.auger@redhat.com>

---
v7 -> v8:
- TCG PAMAX check moved in a separate patch

v6 -> v7
- handle TCG case
- set_memmap modifications moved to previous patches
---
 hw/arm/virt.c | 21 +--------------------
 1 file changed, 1 insertion(+), 20 deletions(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index a3da75a5ae..a45f0fcf79 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -95,21 +95,8 @@
 
 #define PLATFORM_BUS_NUM_IRQS 64
 
-/* RAM limit in GB. Since VIRT_MEM starts at the 1GB mark, this means
- * RAM can go up to the 256GB mark, leaving 256GB of the physical
- * address space unallocated and free for future use between 256G and 512G.
- * If we need to provide more RAM to VMs in the future then we need to:
- *  * allocate a second bank of RAM starting at 2TB and working up
- *  * fix the DT and ACPI table generation code in QEMU to correctly
- *    report two split lumps of RAM to the guest
- *  * fix KVM in the host kernel to allow guests with >40 bit address spaces
- * (We don't want to fill all the way up to 512GB with RAM because
- * we might want it for non-RAM purposes later. Conversely it seems
- * reasonable to assume that anybody configuring a VM with a quarter
- * of a terabyte of RAM will be doing it on a host with more than a
- * terabyte of physical address space.)
- */
 #define RAMBASE GiB
+/* Legacy RAM limit in GB (< version 4.0) */
 #define LEGACY_RAMLIMIT_GB 255
 #define LEGACY_RAMLIMIT_BYTES (LEGACY_RAMLIMIT_GB * GiB)
 
@@ -1515,12 +1502,6 @@ static void machvirt_init(MachineState *machine)
 
     vms->smp_cpus = smp_cpus;
 
-    if (machine->ram_size > vms->memmap[VIRT_MEM].size) {
-        error_report("mach-virt: cannot model more than %dGB RAM",
-                     LEGACY_RAMLIMIT_GB);
-        exit(1);
-    }
-
     if (vms->virt && kvm_enabled()) {
         error_report("mach-virt: KVM does not support providing "
                      "Virtualization extensions to the guest CPU");
-- 
2.20.1

On Thu, 28 Feb 2019 16:03:24 +0100
Eric Auger <eric.auger@redhat.com> wrote:

> Now we have the extended memory map (high IO regions beyond the
> scalable RAM) and dynamic IPA range support at KVM/ARM level
> we can bump the legacy 255GB initial RAM limit. The actual maximum
> RAM size now depends on the physical CPU and host kernel, in
> accelerated mode. In TCG mode, it depends on the VCPU
> AA64MMFR0.PARANGE.
> 
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> 
> ---
> v7 -> v8:
> - TCG PAMAX check moved in a separate patch
> 
> v6 -> v7
> - handle TCG case
> - set_memmap modifications moved to previous patches
> ---
>  hw/arm/virt.c | 21 +--------------------
>  1 file changed, 1 insertion(+), 20 deletions(-)
> 
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index a3da75a5ae..a45f0fcf79 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -95,21 +95,8 @@
>  
>  #define PLATFORM_BUS_NUM_IRQS 64
>  
> -/* RAM limit in GB. Since VIRT_MEM starts at the 1GB mark, this means
> - * RAM can go up to the 256GB mark, leaving 256GB of the physical
> - * address space unallocated and free for future use between 256G and 512G.
> - * If we need to provide more RAM to VMs in the future then we need to:
> - *  * allocate a second bank of RAM starting at 2TB and working up
> - *  * fix the DT and ACPI table generation code in QEMU to correctly
> - *    report two split lumps of RAM to the guest
> - *  * fix KVM in the host kernel to allow guests with >40 bit address spaces
> - * (We don't want to fill all the way up to 512GB with RAM because
> - * we might want it for non-RAM purposes later. Conversely it seems
> - * reasonable to assume that anybody configuring a VM with a quarter
> - * of a terabyte of RAM will be doing it on a host with more than a
> - * terabyte of physical address space.)
> - */
>  #define RAMBASE GiB
> +/* Legacy RAM limit in GB (< version 4.0) */
>  #define LEGACY_RAMLIMIT_GB 255
>  #define LEGACY_RAMLIMIT_BYTES (LEGACY_RAMLIMIT_GB * GiB)
do we need to keep these couple around?

it's used only in
 [VIRT_MEM] = { RAMBASE, LEGACY_RAMLIMIT_BYTES },
and doesn't have any effect whatsoever.
I'd set initial  VIRT_MEM.size to 0 and drop LEGACY_RAMLIMIT_*
maybe add comment above entry that size is defined by ram_size

>  
> @@ -1515,12 +1502,6 @@ static void machvirt_init(MachineState *machine)
>  
>      vms->smp_cpus = smp_cpus;
>  
> -    if (machine->ram_size > vms->memmap[VIRT_MEM].size) {
> -        error_report("mach-virt: cannot model more than %dGB RAM",
> -                     LEGACY_RAMLIMIT_GB);
> -        exit(1);
> -    }
> -
>      if (vms->virt && kvm_enabled()) {
>          error_report("mach-virt: KVM does not support providing "
>                       "Virtualization extensions to the guest CPU");

Hi Igor,

On 2/28/19 5:29 PM, Igor Mammedov wrote:
> On Thu, 28 Feb 2019 16:03:24 +0100
> Eric Auger <eric.auger@redhat.com> wrote:
> 
>> Now we have the extended memory map (high IO regions beyond the
>> scalable RAM) and dynamic IPA range support at KVM/ARM level
>> we can bump the legacy 255GB initial RAM limit. The actual maximum
>> RAM size now depends on the physical CPU and host kernel, in
>> accelerated mode. In TCG mode, it depends on the VCPU
>> AA64MMFR0.PARANGE.
>>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>>
>> ---
>> v7 -> v8:
>> - TCG PAMAX check moved in a separate patch
>>
>> v6 -> v7
>> - handle TCG case
>> - set_memmap modifications moved to previous patches
>> ---
>>  hw/arm/virt.c | 21 +--------------------
>>  1 file changed, 1 insertion(+), 20 deletions(-)
>>
>> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
>> index a3da75a5ae..a45f0fcf79 100644
>> --- a/hw/arm/virt.c
>> +++ b/hw/arm/virt.c
>> @@ -95,21 +95,8 @@
>>  
>>  #define PLATFORM_BUS_NUM_IRQS 64
>>  
>> -/* RAM limit in GB. Since VIRT_MEM starts at the 1GB mark, this means
>> - * RAM can go up to the 256GB mark, leaving 256GB of the physical
>> - * address space unallocated and free for future use between 256G and 512G.
>> - * If we need to provide more RAM to VMs in the future then we need to:
>> - *  * allocate a second bank of RAM starting at 2TB and working up
>> - *  * fix the DT and ACPI table generation code in QEMU to correctly
>> - *    report two split lumps of RAM to the guest
>> - *  * fix KVM in the host kernel to allow guests with >40 bit address spaces
>> - * (We don't want to fill all the way up to 512GB with RAM because
>> - * we might want it for non-RAM purposes later. Conversely it seems
>> - * reasonable to assume that anybody configuring a VM with a quarter
>> - * of a terabyte of RAM will be doing it on a host with more than a
>> - * terabyte of physical address space.)
>> - */
>>  #define RAMBASE GiB
>> +/* Legacy RAM limit in GB (< version 4.0) */
>>  #define LEGACY_RAMLIMIT_GB 255
>>  #define LEGACY_RAMLIMIT_BYTES (LEGACY_RAMLIMIT_GB * GiB)
> do we need to keep these couple around?
> 
> it's used only in
>  [VIRT_MEM] = { RAMBASE, LEGACY_RAMLIMIT_BYTES },
> and doesn't have any effect whatsoever.
> I'd set initial  VIRT_MEM.size to 0 and drop LEGACY_RAMLIMIT_*
> maybe add comment above entry that size is defined by ram_size

in virt_set_memmap I was checking if (high_io_base < 256 GiB) then
high_io_base = 256GiB. Maybe this 256GiB value comes out of the blue and
I should also replace it with vms->memmap[VIRT_MEM].base +
LEGACY_RAMLIMIT_BYTES.
We maintain some kind of compatibility with the old memmap so I prefer
to keep this info somewhere.

I added a comment though:
/* Actual RAM size depends on initial RAM and device memory options */

Thanks

Eric


> 
>>  
>> @@ -1515,12 +1502,6 @@ static void machvirt_init(MachineState *machine)
>>  
>>      vms->smp_cpus = smp_cpus;
>>  
>> -    if (machine->ram_size > vms->memmap[VIRT_MEM].size) {
>> -        error_report("mach-virt: cannot model more than %dGB RAM",
>> -                     LEGACY_RAMLIMIT_GB);
>> -        exit(1);
>> -    }
>> -
>>      if (vms->virt && kvm_enabled()) {
>>          error_report("mach-virt: KVM does not support providing "
>>                       "Virtualization extensions to the guest CPU");
> 

On Fri, 1 Mar 2019 11:08:17 +0100
Auger Eric <eric.auger@redhat.com> wrote:

> Hi Igor,
> 
> On 2/28/19 5:29 PM, Igor Mammedov wrote:
> > On Thu, 28 Feb 2019 16:03:24 +0100
> > Eric Auger <eric.auger@redhat.com> wrote:
> >   
> >> Now we have the extended memory map (high IO regions beyond the
> >> scalable RAM) and dynamic IPA range support at KVM/ARM level
> >> we can bump the legacy 255GB initial RAM limit. The actual maximum
> >> RAM size now depends on the physical CPU and host kernel, in
> >> accelerated mode. In TCG mode, it depends on the VCPU
> >> AA64MMFR0.PARANGE.
> >>
> >> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> >>
> >> ---
> >> v7 -> v8:
> >> - TCG PAMAX check moved in a separate patch
> >>
> >> v6 -> v7
> >> - handle TCG case
> >> - set_memmap modifications moved to previous patches
> >> ---
> >>  hw/arm/virt.c | 21 +--------------------
> >>  1 file changed, 1 insertion(+), 20 deletions(-)
> >>
> >> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> >> index a3da75a5ae..a45f0fcf79 100644
> >> --- a/hw/arm/virt.c
> >> +++ b/hw/arm/virt.c
> >> @@ -95,21 +95,8 @@
> >>  
> >>  #define PLATFORM_BUS_NUM_IRQS 64
> >>  
> >> -/* RAM limit in GB. Since VIRT_MEM starts at the 1GB mark, this means
> >> - * RAM can go up to the 256GB mark, leaving 256GB of the physical
> >> - * address space unallocated and free for future use between 256G and 512G.
> >> - * If we need to provide more RAM to VMs in the future then we need to:
> >> - *  * allocate a second bank of RAM starting at 2TB and working up
> >> - *  * fix the DT and ACPI table generation code in QEMU to correctly
> >> - *    report two split lumps of RAM to the guest
> >> - *  * fix KVM in the host kernel to allow guests with >40 bit address spaces
> >> - * (We don't want to fill all the way up to 512GB with RAM because
> >> - * we might want it for non-RAM purposes later. Conversely it seems
> >> - * reasonable to assume that anybody configuring a VM with a quarter
> >> - * of a terabyte of RAM will be doing it on a host with more than a
> >> - * terabyte of physical address space.)
> >> - */
> >>  #define RAMBASE GiB
> >> +/* Legacy RAM limit in GB (< version 4.0) */
> >>  #define LEGACY_RAMLIMIT_GB 255
> >>  #define LEGACY_RAMLIMIT_BYTES (LEGACY_RAMLIMIT_GB * GiB)  
> > do we need to keep these couple around?
> > 
> > it's used only in
> >  [VIRT_MEM] = { RAMBASE, LEGACY_RAMLIMIT_BYTES },
> > and doesn't have any effect whatsoever.
> > I'd set initial  VIRT_MEM.size to 0 and drop LEGACY_RAMLIMIT_*
> > maybe add comment above entry that size is defined by ram_size  
> 
> in virt_set_memmap I was checking if (high_io_base < 256 GiB) then
> high_io_base = 256GiB. Maybe this 256GiB value comes out of the blue and
> I should also replace it with vms->memmap[VIRT_MEM].base +
> LEGACY_RAMLIMIT_BYTES.
I'd go for it + comment on top of it.

> We maintain some kind of compatibility with the old memmap so I prefer
> to keep this info somewhere.
> 
> I added a comment though:
> /* Actual RAM size depends on initial RAM and device memory options */
> 
> Thanks
> 
> Eric
> 
> 
> >   
> >>  
> >> @@ -1515,12 +1502,6 @@ static void machvirt_init(MachineState *machine)
> >>  
> >>      vms->smp_cpus = smp_cpus;
> >>  
> >> -    if (machine->ram_size > vms->memmap[VIRT_MEM].size) {
> >> -        error_report("mach-virt: cannot model more than %dGB RAM",
> >> -                     LEGACY_RAMLIMIT_GB);
> >> -        exit(1);
> >> -    }
> >> -
> >>      if (vms->virt && kvm_enabled()) {
> >>          error_report("mach-virt: KVM does not support providing "
> >>                       "Virtualization extensions to the guest CPU");  
> >