1. Patchew
  2. Libvirt
  3. [PATCH v2 0/3] Add virt machine support for configuring PCI high memory MMIO size
  4. View patch

[PATCH v2 2/3] qemu: Add command line support for PCI high memory MMIO size

Matthew R. Ochs via Devel posted 3 patches 9 months ago
There is a newer version of this series
[PATCH v2 2/3] qemu: Add command line support for PCI high memory MMIO size
Posted by Matthew R. Ochs via Devel 9 months ago 
Add support for generating QEMU command line with PCI high memory MMIO size:
    - Add highmem-mmio-size to machine command line generation using
      size conveyed through pcihole64
    - Add validation for aarch64/virt machine type requirement
    - Add capability check for QEMU support

This enables configuring the PCI high memory MMIO window size
for aarch64 virt machine types using the existing pcihole64
element.

Signed-off-by: Matthew R. Ochs <mochs@nvidia.com>
---
 src/qemu/qemu_command.c  | 14 +++++++++++++-
 src/qemu/qemu_validate.c |  8 ++++++--
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index e6d308534f87..1386b2772a55 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -6195,7 +6195,8 @@ qemuBuildGlobalControllerCommandLine(virCommand *cmd,
     for (i = 0; i < def->ncontrollers; i++) {
         virDomainControllerDef *cont = def->controllers[i];
         if (cont->type == VIR_DOMAIN_CONTROLLER_TYPE_PCI &&
-            cont->opts.pciopts.pcihole64) {
+            cont->opts.pciopts.pcihole64 &&
+            !qemuDomainIsARMVirt(def)) {
             const char *hoststr = NULL;
 
             switch (cont->model) {
@@ -7112,6 +7113,17 @@ qemuBuildMachineCommandLine(virCommand *cmd,
 
     qemuBuildMachineACPI(&buf, def, qemuCaps);
 
+    if (qemuDomainIsARMVirt(def)) {
+        for (i = 0; i < def->ncontrollers; i++) {
+            virDomainControllerDef *cont = def->controllers[i];
+            if (cont->type == VIR_DOMAIN_CONTROLLER_TYPE_PCI &&
+                cont->opts.pciopts.pcihole64) {
+                virBufferAsprintf(&buf, ",highmem-mmio-size=%lluK", cont->opts.pciopts.pcihole64size);
+                break;
+            }
+        }
+    }
+
     virCommandAddArgBuffer(cmd, &buf);
 
     return 0;
diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c
index b2c3c9e2f631..f808aac1063a 100644
--- a/src/qemu/qemu_validate.c
+++ b/src/qemu/qemu_validate.c
@@ -4074,7 +4074,9 @@ qemuValidateDomainDeviceDefControllerPCI(const virDomainControllerDef *cont,
     switch ((virDomainControllerModelPCI) cont->model) {
     case VIR_DOMAIN_CONTROLLER_MODEL_PCI_ROOT:
         if (pciopts->pcihole64 ||  pciopts->pcihole64size != 0) {
-            if (!qemuDomainIsI440FX(def)) {
+            if (!qemuDomainIsI440FX(def) &&
+                !(qemuDomainIsARMVirt(def) && virQEMUCapsGet(qemuCaps,
+                                                             QEMU_CAPS_MACHINE_VIRT_HIGHMEM_MMIO_SIZE))) {
                 virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                                _("Setting the 64-bit PCI hole size is not supported for machine '%1$s'"),
                                def->os.machine);
@@ -4085,7 +4087,9 @@ qemuValidateDomainDeviceDefControllerPCI(const virDomainControllerDef *cont,
 
     case VIR_DOMAIN_CONTROLLER_MODEL_PCIE_ROOT:
         if (pciopts->pcihole64 || pciopts->pcihole64size != 0) {
-            if (!qemuDomainIsQ35(def)) {
+            if (!qemuDomainIsQ35(def) &&
+                !(qemuDomainIsARMVirt(def) && virQEMUCapsGet(qemuCaps,
+                                                             QEMU_CAPS_MACHINE_VIRT_HIGHMEM_MMIO_SIZE))) {
                 virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                                _("Setting the 64-bit PCI hole size is not supported for machine '%1$s'"),
                                def->os.machine);
-- 
2.46.0
Re: [PATCH v2 2/3] qemu: Add command line support for PCI high memory MMIO size
Posted by Daniel P. Berrangé via Devel 8 months, 4 weeks ago 
On Wed, May 14, 2025 at 05:18:50PM -0700, Matthew R. Ochs wrote:
> Add support for generating QEMU command line with PCI high memory MMIO size:
>     - Add highmem-mmio-size to machine command line generation using
>       size conveyed through pcihole64
>     - Add validation for aarch64/virt machine type requirement
>     - Add capability check for QEMU support
> 
> This enables configuring the PCI high memory MMIO window size
> for aarch64 virt machine types using the existing pcihole64
> element.
> 
> Signed-off-by: Matthew R. Ochs <mochs@nvidia.com>
> ---
>  src/qemu/qemu_command.c  | 14 +++++++++++++-
>  src/qemu/qemu_validate.c |  8 ++++++--
>  2 files changed, 19 insertions(+), 3 deletions(-)
> 
> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index e6d308534f87..1386b2772a55 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
> @@ -6195,7 +6195,8 @@ qemuBuildGlobalControllerCommandLine(virCommand *cmd,
>      for (i = 0; i < def->ncontrollers; i++) {
>          virDomainControllerDef *cont = def->controllers[i];
>          if (cont->type == VIR_DOMAIN_CONTROLLER_TYPE_PCI &&
> -            cont->opts.pciopts.pcihole64) {
> +            cont->opts.pciopts.pcihole64 &&
> +            !qemuDomainIsARMVirt(def)) {

This ought to be a positive check

..IsQ35(..) || ..IsI440FX(..)

>              const char *hoststr = NULL;
>  
>              switch (cont->model) {
> @@ -7112,6 +7113,17 @@ qemuBuildMachineCommandLine(virCommand *cmd,
>  
>      qemuBuildMachineACPI(&buf, def, qemuCaps);
>  
> +    if (qemuDomainIsARMVirt(def)) {
> +        for (i = 0; i < def->ncontrollers; i++) {
> +            virDomainControllerDef *cont = def->controllers[i];
> +            if (cont->type == VIR_DOMAIN_CONTROLLER_TYPE_PCI &&
> +                cont->opts.pciopts.pcihole64) {
> +                virBufferAsprintf(&buf, ",highmem-mmio-size=%lluK", cont->opts.pciopts.pcihole64size);
> +                break;
> +            }
> +        }
> +    }
> +
>      virCommandAddArgBuffer(cmd, &buf);
>  
>      return 0;
> diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c
> index b2c3c9e2f631..f808aac1063a 100644
> --- a/src/qemu/qemu_validate.c
> +++ b/src/qemu/qemu_validate.c
> @@ -4074,7 +4074,9 @@ qemuValidateDomainDeviceDefControllerPCI(const virDomainControllerDef *cont,
>      switch ((virDomainControllerModelPCI) cont->model) {
>      case VIR_DOMAIN_CONTROLLER_MODEL_PCI_ROOT:
>          if (pciopts->pcihole64 ||  pciopts->pcihole64size != 0) {
> -            if (!qemuDomainIsI440FX(def)) {
> +            if (!qemuDomainIsI440FX(def) &&
> +                !(qemuDomainIsARMVirt(def) && virQEMUCapsGet(qemuCaps,
> +                                                             QEMU_CAPS_MACHINE_VIRT_HIGHMEM_MMIO_SIZE))) {
>                  virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
>                                 _("Setting the 64-bit PCI hole size is not supported for machine '%1$s'"),
>                                 def->os.machine);

IIUC arm virt machine is always PCI-E, so we shouldn't allow it
for arm here.

> @@ -4085,7 +4087,9 @@ qemuValidateDomainDeviceDefControllerPCI(const virDomainControllerDef *cont,
>  
>      case VIR_DOMAIN_CONTROLLER_MODEL_PCIE_ROOT:
>          if (pciopts->pcihole64 || pciopts->pcihole64size != 0) {
> -            if (!qemuDomainIsQ35(def)) {
> +            if (!qemuDomainIsQ35(def) &&
> +                !(qemuDomainIsARMVirt(def) && virQEMUCapsGet(qemuCaps,
> +                                                             QEMU_CAPS_MACHINE_VIRT_HIGHMEM_MMIO_SIZE))) {
>                  virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
>                                 _("Setting the 64-bit PCI hole size is not supported for machine '%1$s'"),
>                                 def->os.machine);
> -- 
> 2.46.0
> 

With regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|
Re: [PATCH v2 2/3] qemu: Add command line support for PCI high memory MMIO size
Posted by Matt Ochs via Devel 8 months, 4 weeks ago 
> On May 15, 2025, at 6:54 AM, Daniel P. Berrangé <berrange@redhat.com> wrote:
> On Wed, May 14, 2025 at 05:18:50PM -0700, Matthew R. Ochs wrote:
>> Add support for generating QEMU command line with PCI high memory MMIO size:
>>    - Add highmem-mmio-size to machine command line generation using
>>      size conveyed through pcihole64
>>    - Add validation for aarch64/virt machine type requirement
>>    - Add capability check for QEMU support
>> 
>> This enables configuring the PCI high memory MMIO window size
>> for aarch64 virt machine types using the existing pcihole64
>> element.
>> 
>> Signed-off-by: Matthew R. Ochs <mochs@nvidia.com>
>> ---
>> src/qemu/qemu_command.c  | 14 +++++++++++++-
>> src/qemu/qemu_validate.c |  8 ++++++--
>> 2 files changed, 19 insertions(+), 3 deletions(-)
>> 
>> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
>> index e6d308534f87..1386b2772a55 100644
>> --- a/src/qemu/qemu_command.c
>> +++ b/src/qemu/qemu_command.c
>> @@ -6195,7 +6195,8 @@ qemuBuildGlobalControllerCommandLine(virCommand *cmd,
>>     for (i = 0; i < def->ncontrollers; i++) {
>>         virDomainControllerDef *cont = def->controllers[i];
>>         if (cont->type == VIR_DOMAIN_CONTROLLER_TYPE_PCI &&
>> -            cont->opts.pciopts.pcihole64) {
>> +            cont->opts.pciopts.pcihole64 &&
>> +            !qemuDomainIsARMVirt(def)) {
> 
> This ought to be a positive check
> 
> ..IsQ35(..) || ..IsI440FX(..)

Makes sense, will fix in v3.

>> 
>> diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c
>> index b2c3c9e2f631..f808aac1063a 100644
>> --- a/src/qemu/qemu_validate.c
>> +++ b/src/qemu/qemu_validate.c
>> @@ -4074,7 +4074,9 @@ qemuValidateDomainDeviceDefControllerPCI(const virDomainControllerDef *cont,
>>     switch ((virDomainControllerModelPCI) cont->model) {
>>     case VIR_DOMAIN_CONTROLLER_MODEL_PCI_ROOT:
>>         if (pciopts->pcihole64 ||  pciopts->pcihole64size != 0) {
>> -            if (!qemuDomainIsI440FX(def)) {
>> +            if (!qemuDomainIsI440FX(def) &&
>> +                !(qemuDomainIsARMVirt(def) && virQEMUCapsGet(qemuCaps,
>> +                                                             QEMU_CAPS_MACHINE_VIRT_HIGHMEM_MMIO_SIZE))) {
>>                 virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
>>                                _("Setting the 64-bit PCI hole size is not supported for machine '%1$s'"),
>>                                def->os.machine);
> 
> IIUC arm virt machine is always PCI-E, so we shouldn't allow it
> for arm here.

Yep, will remove this change in v3.

Patchew 2.1-devel-b67e4c2

© 2016 - 2026 Red Hat, Inc.