commit acf7e2c93cb3efda0add6fd5f3b5b447e63d6367 (HEAD -> master)
Author: paulian <paulian@marinca.net>
Date:   Sun Apr 12 18:08:45 2026 +0300

    hw/i386/intel_iommu: advertise PT in ECAP, not CAP

    Commit c7b2e22bd957 ("hw/i386/x86-iommu: Remove X86IOMMUState::pt_supported
    field") made pass-through translation type always supported, but moved
    VTD_ECAP_PT into s->cap in vtd_cap_init().

    VTD_ECAP_PT is an ECAP bit, not a CAP bit, and the rest of the VT-d code
    checks it via s->ecap. Advertise PT in s->ecap and stop setting the bit in
    s->cap.

    Fixes: c7b2e22bd957 ("hw/i386/x86-iommu: Remove
X86IOMMUState::pt_supported field")
    Signed-off-by: Paulian Marinca <paulian@marinca.net>

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index f395fa248c..7b2cead8f8 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -4998,7 +4998,7 @@ static void vtd_cap_init(IntelIOMMUState *s)
 {
     X86IOMMUState *x86_iommu = X86_IOMMU_DEVICE(s);

-    s->cap = VTD_CAP_FRO | VTD_CAP_NFR | VTD_CAP_ND | VTD_ECAP_PT |
+    s->cap = VTD_CAP_FRO | VTD_CAP_NFR | VTD_CAP_ND |
              VTD_CAP_MAMV | VTD_CAP_PSI | VTD_CAP_SSLPS | VTD_CAP_DRAIN |
              VTD_CAP_ESRTPS | VTD_CAP_MGAW(s->aw_bits);
     if (x86_iommu->dma_translation) {
@@ -5009,7 +5009,7 @@ static void vtd_cap_init(IntelIOMMUState *s)
                     s->cap |= VTD_CAP_SAGAW_48bit;
             }
     }
-    s->ecap = VTD_ECAP_QI | VTD_ECAP_IRO;
+    s->ecap = VTD_ECAP_QI | VTD_ECAP_IRO | VTD_ECAP_PT;

     if (x86_iommu_ir_supported(x86_iommu)) {
         s->ecap |= VTD_ECAP_IR | VTD_ECAP_MHMV;

Good catch!

Reviewed-by: Clement Mathieu--Drif <clement.mathieu--drif@bull.com>

Thanks

On Sun, 2026-04-12 at 18:17 +0300, Paulian Bogdan Marinca wrote:
> commit acf7e2c93cb3efda0add6fd5f3b5b447e63d6367 (HEAD -> master)  
> Author: paulian <[paulian@marinca.net](mailto:paulian@marinca.net)>  
> Date:   Sun Apr 12 18:08:45 2026 +0300
> 
>     hw/i386/intel_iommu: advertise PT in ECAP, not CAP
> 
>     Commit c7b2e22bd957 ("hw/i386/x86-iommu: Remove X86IOMMUState::pt_supported  
>     field") made pass-through translation type always supported, but moved  
>     VTD_ECAP_PT into s->cap in vtd_cap_init().
> 
>     VTD_ECAP_PT is an ECAP bit, not a CAP bit, and the rest of the VT-d code  
>     checks it via s->ecap. Advertise PT in s->ecap and stop setting the bit in  
>     s->cap.
> 
>     Fixes: c7b2e22bd957 ("hw/i386/x86-iommu: Remove  
> X86IOMMUState::pt_supported field")  
>     Signed-off-by: Paulian Marinca <[paulian@marinca.net](mailto:paulian@marinca.net)>
> 
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c  
> index f395fa248c..7b2cead8f8 100644  
> --- a/hw/i386/intel_iommu.c  
> +++ b/hw/i386/intel_iommu.c  
> @@ -4998,7 +4998,7 @@ static void vtd_cap_init(IntelIOMMUState *s)  
>  {  
>      X86IOMMUState *x86_iommu = X86_IOMMU_DEVICE(s);
> 
> -    s->cap = VTD_CAP_FRO | VTD_CAP_NFR | VTD_CAP_ND | VTD_ECAP_PT |  
> +    s->cap = VTD_CAP_FRO | VTD_CAP_NFR | VTD_CAP_ND |  
>               VTD_CAP_MAMV | VTD_CAP_PSI | VTD_CAP_SSLPS | VTD_CAP_DRAIN |  
>               VTD_CAP_ESRTPS | VTD_CAP_MGAW(s->aw_bits);  
>      if (x86_iommu->dma_translation) {  
> @@ -5009,7 +5009,7 @@ static void vtd_cap_init(IntelIOMMUState *s)  
>                      s->cap |= VTD_CAP_SAGAW_48bit;  
>              }  
>      }  
> -    s->ecap = VTD_ECAP_QI | VTD_ECAP_IRO;  
> +    s->ecap = VTD_ECAP_QI | VTD_ECAP_IRO | VTD_ECAP_PT;
> 
>      if (x86_iommu_ir_supported(x86_iommu)) {  
>          s->ecap |= VTD_ECAP_IR | VTD_ECAP_MHMV;
>