On 2/22/21 6:24 PM, Cornelia Huck wrote:

On Fri, 19 Feb 2021 18:38:37 +0100
Philippe Mathieu-Daudé [off-list ref] wrote:

quoted

MachineClass::kvm_type() can return -1 on failure.
Document it, and add a check in kvm_init().

Signed-off-by: Philippe Mathieu-Daudé <redacted>
---
 include/hw/boards.h | 3 ++-
 accel/kvm/kvm-all.c | 6 ++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/include/hw/boards.h b/include/hw/boards.h
index a46dfe5d1a6..68d3d10f6b0 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h

@@ -127,7 +127,8 @@ typedef struct {
  *    implement and a stub device is required.
  * @kvm_type:
  *    Return the type of KVM corresponding to the kvm-type string option or
- *    computed based on other criteria such as the host kernel capabilities.
+ *    computed based on other criteria such as the host kernel capabilities
+ *    (which can't be negative), or -1 on error.
  * @numa_mem_supported:
  *    true if '--numa node.mem' option is supported and false otherwise
  * @smp_parse:

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 84c943fcdb2..b069938d881 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c

@@ -2057,6 +2057,12 @@ static int kvm_init(MachineState *ms)
                                                             "kvm-type",
                                                             &error_abort);
         type = mc->kvm_type(ms, kvm_type);
+        if (type < 0) {
+            ret = -EINVAL;
+            fprintf(stderr, "Failed to detect kvm-type for machine '%s'\n",
+                    mc->name);
+            goto err;
+        }
     }
 
     do {

No objection to this patch; but I'm wondering why some non-pseries
machines implement the kvm_type callback, when I see the kvm-type
property only for pseries? Am I holding my git grep wrong?

Can it be what David commented here?
https://www.mail-archive.com/qemu-devel@nongnu.org/msg784508.html