Re: [RFC PATCH v4 06/36] i386/tdx: Get tdx_capabilities via KVM_TDX_CAPABILITIES

[Isaku Yamahata <isaku.yamahata@gmail.com>]

On Thu, May 12, 2022 at 11:17:33AM +0800,
Xiaoyao Li <xiaoyao.li@intel.com> wrote:

> KVM provides TDX capabilities via sub command KVM_TDX_CAPABILITIES of
> IOCTL(KVM_MEMORY_ENCRYPT_OP). Get the capabilities when initializing
> TDX context. It will be used to validate user's setting later.
> 
> Besides, introduce the interfaces to invoke TDX "ioctls" at different
> scope (KVM, VM and VCPU) in preparation.
> 
> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> ---
>  target/i386/kvm/tdx.c | 85 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 85 insertions(+)
> 
> diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
> index 77e33ae01147..68bedbad0ebe 100644
> --- a/target/i386/kvm/tdx.c
> +++ b/target/i386/kvm/tdx.c
> @@ -14,12 +14,97 @@
>  #include "qemu/osdep.h"
>  #include "qapi/error.h"
>  #include "qom/object_interfaces.h"
> +#include "sysemu/kvm.h"
>  
>  #include "hw/i386/x86.h"
>  #include "tdx.h"
>  
> +enum tdx_ioctl_level{
> +    TDX_PLATFORM_IOCTL,
> +    TDX_VM_IOCTL,
> +    TDX_VCPU_IOCTL,
> +};
> +
> +static int __tdx_ioctl(void *state, enum tdx_ioctl_level level, int cmd_id,
> +                        __u32 flags, void *data)
> +{
> +    struct kvm_tdx_cmd tdx_cmd;
> +    int r;
> +
> +    memset(&tdx_cmd, 0x0, sizeof(tdx_cmd));
> +
> +    tdx_cmd.id = cmd_id;
> +    tdx_cmd.flags = flags;
> +    tdx_cmd.data = (__u64)(unsigned long)data;
> +
> +    switch (level) {
> +    case TDX_PLATFORM_IOCTL:
> +        r = kvm_ioctl(kvm_state, KVM_MEMORY_ENCRYPT_OP, &tdx_cmd);
> +        break;
> +    case TDX_VM_IOCTL:
> +        r = kvm_vm_ioctl(kvm_state, KVM_MEMORY_ENCRYPT_OP, &tdx_cmd);
> +        break;
> +    case TDX_VCPU_IOCTL:
> +        r = kvm_vcpu_ioctl(state, KVM_MEMORY_ENCRYPT_OP, &tdx_cmd);
> +        break;
> +    default:
> +        error_report("Invalid tdx_ioctl_level %d", level);
> +        exit(1);
> +    }
> +
> +    return r;
> +}
> +
> +static inline int tdx_platform_ioctl(int cmd_id, __u32 metadata, void *data)

nitpick:  Because metadata was renamed to flags for clarity, please update
those.

> +{
> +    return __tdx_ioctl(NULL, TDX_PLATFORM_IOCTL, cmd_id, metadata, data);
> +}
> +
> +static inline int tdx_vm_ioctl(int cmd_id, __u32 metadata, void *data)
> +{
> +    return __tdx_ioctl(NULL, TDX_VM_IOCTL, cmd_id, metadata, data);
> +}
> +
> +static inline int tdx_vcpu_ioctl(void *vcpu_fd, int cmd_id, __u32 metadata,
> +                                 void *data)
> +{
> +    return  __tdx_ioctl(vcpu_fd, TDX_VCPU_IOCTL, cmd_id, metadata, data);
> +}
> +
> +static struct kvm_tdx_capabilities *tdx_caps;
> +
> +static void get_tdx_capabilities(void)
> +{
> +    struct kvm_tdx_capabilities *caps;
> +    int max_ent = 1;

Because we know the number of entries for TDX 1.0. We can start with better
value with comment on it.


> +    int r, size;
> +
> +    do {
> +        size = sizeof(struct kvm_tdx_capabilities) +
> +               max_ent * sizeof(struct kvm_tdx_cpuid_config);
> +        caps = g_malloc0(size);
> +        caps->nr_cpuid_configs = max_ent;
> +
> +        r = tdx_platform_ioctl(KVM_TDX_CAPABILITIES, 0, caps);
> +        if (r == -E2BIG) {
> +            g_free(caps);
> +            max_ent *= 2;
> +        } else if (r < 0) {
> +            error_report("KVM_TDX_CAPABILITIES failed: %s\n", strerror(-r));
> +            exit(1);
> +        }
> +    }
> +    while (r == -E2BIG);
> +
> +    tdx_caps = caps;
> +}
> +
>  int tdx_kvm_init(MachineState *ms, Error **errp)
>  {
> +    if (!tdx_caps) {
> +        get_tdx_capabilities();
> +    }
> +
>      return 0;
>  }
>  
> -- 
> 2.27.0
> 
> 

-- 
Isaku Yamahata <isaku.yamahata@gmail.com>