Re: [PATCH v6 13/60] i386/tdx: Validate TD attributes

[Daniel P . Berrangé]

On Tue, Nov 05, 2024 at 01:23:21AM -0500, Xiaoyao Li wrote:
> Validate TD attributes with tdx_caps that fixed-0 bits must be zero and
> fixed-1 bits must be set.
> 
> Besides, sanity check the attribute bits that have not been supported by
> QEMU yet. e.g., debug bit, it will be allowed in the future when debug
> TD support lands in QEMU.
> 
> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> Acked-by: Gerd Hoffmann <kraxel@redhat.com>
> 
> ---
> Changes in v3:
> - using error_setg() for error report; (Daniel)
> ---
>  target/i386/kvm/tdx.c | 28 ++++++++++++++++++++++++++--
>  1 file changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
> index 6cf81f788fe0..5a9ce2ada89d 100644
> --- a/target/i386/kvm/tdx.c
> +++ b/target/i386/kvm/tdx.c
> @@ -20,6 +20,7 @@
>  #include "kvm_i386.h"
>  #include "tdx.h"
>  
> +#define TDX_TD_ATTRIBUTES_DEBUG             BIT_ULL(0)
>  #define TDX_TD_ATTRIBUTES_SEPT_VE_DISABLE   BIT_ULL(28)
>  #define TDX_TD_ATTRIBUTES_PKS               BIT_ULL(30)
>  #define TDX_TD_ATTRIBUTES_PERFMON           BIT_ULL(63)
> @@ -141,13 +142,33 @@ static int tdx_kvm_type(X86ConfidentialGuest *cg)
>      return KVM_X86_TDX_VM;
>  }
>  
> -static void setup_td_guest_attributes(X86CPU *x86cpu)
> +static int tdx_validate_attributes(TdxGuest *tdx, Error **errp)
> +{
> +    if ((tdx->attributes & ~tdx_caps->supported_attrs)) {
> +            error_setg(errp, "Invalid attributes 0x%lx for TDX VM "
> +                       "(supported: 0x%llx)",
> +                       tdx->attributes, tdx_caps->supported_attrs);
> +            return -1;

Minor whitespace accident, with indentation too deep.

> +    }
> +
> +    if (tdx->attributes & TDX_TD_ATTRIBUTES_DEBUG) {
> +        error_setg(errp, "Current QEMU doesn't support attributes.debug[bit 
> 0] "
> +                         "for TDX VM");
> +        return -1;
> +    }
> +
> +    return 0;
> +}

With regards,
Daniel
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