At this moment it is not possible to launch a 'riscv64' domain if a CPU
definition is presented in the domain. For example, adding this CPU
definition:

  <cpu mode='custom' match='exact' check='none'>
    <model fallback='forbid'>rv64</model>
  </cpu>

Will trigger the following error:

$ sudo ./run tools/virsh start riscv-virt1
error: Failed to start domain 'riscv-virt1'
error: this function is not supported by the connection driver:
       cannot update guest CPU for riscv64 architecture

The error comes from virCPUUpdate(), via qemuProcessUpdateGuestCPU(),
and it's caused by the absence of the 'update' API in the existing
RISC-V driver.

Add an 'update' API impl to the RISC-V driver to allow for CPU
definitions to be declared in RISC-V domains. This API was copied from
the ARM driver (virCPUarmUpdate()) since it's a good enough
implementation to get us going.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 po/POTFILES           |  1 +
 src/cpu/cpu_riscv64.c | 28 +++++++++++++++++++++++++++-
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/po/POTFILES b/po/POTFILES
index b122f02818..5d6ec195b4 100644
--- a/po/POTFILES
+++ b/po/POTFILES
@@ -70,6 +70,7 @@ src/cpu/cpu.c
 src/cpu/cpu_arm.c
 src/cpu/cpu_map.c
 src/cpu/cpu_ppc64.c
+src/cpu/cpu_riscv64.c
 src/cpu/cpu_s390.c
 src/cpu/cpu_x86.c
 src/datatypes.c
diff --git a/src/cpu/cpu_riscv64.c b/src/cpu/cpu_riscv64.c
index c44bdeb291..4cb795f849 100644
--- a/src/cpu/cpu_riscv64.c
+++ b/src/cpu/cpu_riscv64.c
@@ -46,6 +46,32 @@ virCPURiscv64ValidateFeatures(virCPUDef *cpu G_GNUC_UNUSED)
 }
 
 
+static int
+virCPURiscv64Update(virCPUDef *guest,
+                    const virCPUDef *host,
+                    bool relative)
+{
+    g_autoptr(virCPUDef) updated = virCPUDefCopyWithoutModel(guest);
+
+    if (!relative || guest->mode != VIR_CPU_MODE_HOST_MODEL)
+        return 0;
+
+    if (!host) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("unknown host CPU model"));
+        return -1;
+    }
+
+    updated->mode = VIR_CPU_MODE_CUSTOM;
+    virCPUDefCopyModel(updated, host, true);
+
+    virCPUDefStealModel(guest, updated, false);
+    guest->mode = VIR_CPU_MODE_CUSTOM;
+    guest->match = VIR_CPU_MATCH_EXACT;
+
+    return 0;
+}
+
 struct cpuArchDriver cpuDriverRiscv64 = {
     .name = "riscv64",
     .arch = archs,
@@ -54,6 +80,6 @@ struct cpuArchDriver cpuDriverRiscv64 = {
     .decode     = NULL,
     .encode     = NULL,
     .baseline   = NULL,
-    .update     = NULL,
+    .update     = virCPURiscv64Update,
     .validateFeatures = virCPURiscv64ValidateFeatures,
 };
-- 
2.40.0

On Wed, Jan 22, 2025 at 12:16:59PM -0300, Daniel Henrique Barboza wrote:
>At this moment it is not possible to launch a 'riscv64' domain if a CPU
>definition is presented in the domain. For example, adding this CPU
>definition:
>
>  <cpu mode='custom' match='exact' check='none'>
>    <model fallback='forbid'>rv64</model>
>  </cpu>
>
>Will trigger the following error:
>
>$ sudo ./run tools/virsh start riscv-virt1
>error: Failed to start domain 'riscv-virt1'
>error: this function is not supported by the connection driver:
>       cannot update guest CPU for riscv64 architecture
>
>The error comes from virCPUUpdate(), via qemuProcessUpdateGuestCPU(),
>and it's caused by the absence of the 'update' API in the existing
>RISC-V driver.
>
>Add an 'update' API impl to the RISC-V driver to allow for CPU
>definitions to be declared in RISC-V domains. This API was copied from
>the ARM driver (virCPUarmUpdate()) since it's a good enough
>implementation to get us going.
>
>Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>

I presume this patch was left formatted in your repo and accidentally
sent with something like `git send-email *patch`, since it's already
merged for quite some time =)

Anyway, thanks to it I noticed the change in your e-mail address, so you
might want to update .mailmap to your satisfaction.

Martin

On 1/23/25 6:18 AM, Martin Kletzander wrote:
> On Wed, Jan 22, 2025 at 12:16:59PM -0300, Daniel Henrique Barboza wrote:
>> At this moment it is not possible to launch a 'riscv64' domain if a CPU
>> definition is presented in the domain. For example, adding this CPU
>> definition:
>>
>>  <cpu mode='custom' match='exact' check='none'>
>>    <model fallback='forbid'>rv64</model>
>>  </cpu>
>>
>> Will trigger the following error:
>>
>> $ sudo ./run tools/virsh start riscv-virt1
>> error: Failed to start domain 'riscv-virt1'
>> error: this function is not supported by the connection driver:
>>       cannot update guest CPU for riscv64 architecture
>>
>> The error comes from virCPUUpdate(), via qemuProcessUpdateGuestCPU(),
>> and it's caused by the absence of the 'update' API in the existing
>> RISC-V driver.
>>
>> Add an 'update' API impl to the RISC-V driver to allow for CPU
>> definitions to be declared in RISC-V domains. This API was copied from
>> the ARM driver (virCPUarmUpdate()) since it's a good enough
>> implementation to get us going.
>>
>> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> 
> I presume this patch was left formatted in your repo and accidentally
> sent with something like `git send-email *patch`, since it's already
> merged for quite some time =)

Oooops :(

> 
> Anyway, thanks to it I noticed the change in your e-mail address, so you
> might want to update .mailmap to your satisfaction.

I wasn't aware of this file. I'll take a look and update as needed. Thanks,


Daniel


> 
> Martin