Re: [PATCH v6 40/60] hw/i386: add eoi_intercept_unsupported member to X86MachineState

Igor Mammedov
2025-01-23T12:41:54Z

On Tue, 5 Nov 2024 01:23:48 -0500
Xiaoyao Li <xiaoyao.li@intel.com> wrote:

> Add a new bool member, eoi_intercept_unsupported, to X86MachineState
> with default value false. Set true for TDX VM.

I'd rename it to enable_eoi_intercept, by default set to true for evrything
and make TDX override this to false.
>
> Inability to intercept eoi causes impossibility to emulate level
> triggered interrupt to be re-injected when level is still kept active.
> which affects interrupt controller emulation.
>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> Acked-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
> hw/i386/x86.c | 1 +
> include/hw/i386/x86.h | 1 +
> target/i386/kvm/tdx.c | 2 ++
> 3 files changed, 4 insertions(+)
>
> diff --git a/hw/i386/x86.c b/hw/i386/x86.c
> index 01fc5e656272..82faeed24ff9 100644
> --- a/hw/i386/x86.c
> +++ b/hw/i386/x86.c
> @@ -370,6 +370,7 @@ static void x86_machine_initfn(Object *obj)
> x86ms->oem_table_id = g_strndup(ACPI_BUILD_APPNAME8, 8);
> x86ms->bus_lock_ratelimit = 0;
> x86ms->above_4g_mem_start = 4 * GiB;
> + x86ms->eoi_intercept_unsupported = false;
> }
>
> static void x86_machine_class_init(ObjectClass *oc, void *data)
> diff --git a/include/hw/i386/x86.h b/include/hw/i386/x86.h
> index d43cb3908e65..fd9a30391755 100644
> --- a/include/hw/i386/x86.h
> +++ b/include/hw/i386/x86.h
> @@ -73,6 +73,7 @@ struct X86MachineState {
> uint64_t above_4g_mem_start;
>
> /* CPU and apic information: */
> + bool eoi_intercept_unsupported;
> unsigned pci_irq_mask;
> unsigned apic_id_limit;
> uint16_t boot_cpus;
> diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
> index 9ab4e911f78a..9dcb77e011bd 100644
> --- a/target/i386/kvm/tdx.c
> +++ b/target/i386/kvm/tdx.c
> @@ -388,6 +388,8 @@ static int tdx_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
> return -EOPNOTSUPP;
> }
>
> + x86ms->eoi_intercept_unsupported = true;

I don't particulary like accel go to its parent (machine) object and override things there
and that being buried deep inside.

How do you start TDX guest?
Is there a machine property or something like it to enable TDX?

> +
> /*
> * Set kvm_readonly_mem_allowed to false, because TDX only supports readonly
> * memory for shared memory but not for private memory. Besides, whether a