[libvirt] [PATCH 09/11] qemu: Move capability checks for IOMMU features

[Ján Tomko]

On Tue, May 28, 2019 at 05:29:02PM +0200, Andrea Bolognani wrote:
>All current IOMMU features are specific to Intel IOMMU, so
>understandably we check for the corresponding capabilities
>inside the Intel-specific switch() branch; however, we want
>to make sure SMMUv3 IOMMU users get an error if they try to
>enable any of those features in their guest, and performing
>the capability checks unconditionally is both the easiest
>way to achieve that, as well as the one least likely to
>result in us inadvertently letting users enable some new
>Intel-specific IOMMU feature for ARM guests later on.
>
>Signed-off-by: Andrea Bolognani <abologna at redhat.com>
>---
> src/qemu/qemu_domain.c | 63 +++++++++++++++++++++++-------------------
> 1 file changed, 35 insertions(+), 28 deletions(-)
>
>@@ -6158,6 +6130,41 @@ qemuDomainDeviceDefValidateIOMMU(const virDomainIOMMUDef *iommu,
>         return -1;
>     }
>
>+    /* These capability checks ensure we're not trying to use features
>+     * of Intel IOMMU that the QEMU binary does not support, but they
>+     * also make sure we report an error when trying to use features
>+     * that are not implemented by SMMUv3,

> so they must be here instead
>+     * of inside the switch() statement above */

This part of the sentence is not really necessary.

>+
>+    if (iommu->intremap != VIR_TRISTATE_SWITCH_ABSENT &&
>+        !virQEMUCapsGet(qemuCaps, QEMU_CAPS_INTEL_IOMMU_INTREMAP)) {
>+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
>+                       _("iommu: interrupt remapping is not supported "
>+                         "with this QEMU binary"));
>+        return -1;
>+    }

Reviewed-by: Ján Tomko <jtomko at redhat.com>

Jano
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