diff mbox series

[v3,18/70] i386/tdx: Get tdx_capabilities via KVM_TDX_CAPABILITIES

Message ID 20231115071519.2864957-19-xiaoyao.li@intel.com (mailing list archive)
State New, archived
Headers show
Series QEMU Guest memfd + QEMU TDX support | expand

Commit Message

Xiaoyao Li Nov. 15, 2023, 7:14 a.m. UTC
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.

Since there is no interface reporting how many cpuid configs contains in
KVM_TDX_CAPABILITIES, QEMU chooses to try starting with a known number
and abort when it exceeds KVM_MAX_CPUID_ENTRIES.

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>
---
Changes in v3:
- rename __tdx_ioctl() to tdx_ioctl_internal()
- Pass errp in get_tdx_capabilities();

changes in v2:
  - Make the error message more clear;

changes in v1:
  - start from nr_cpuid_configs = 6 for the loop;
  - stop the loop when nr_cpuid_configs exceeds KVM_MAX_CPUID_ENTRIES;
---
 target/i386/kvm/kvm.c      |   2 -
 target/i386/kvm/kvm_i386.h |   2 +
 target/i386/kvm/tdx.c      | 102 ++++++++++++++++++++++++++++++++++++-
 3 files changed, 103 insertions(+), 3 deletions(-)

Comments

Daniel P. Berrangé Nov. 15, 2023, 10:54 a.m. UTC | #1
On Wed, Nov 15, 2023 at 02:14:27AM -0500, Xiaoyao Li 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.
> 
> Since there is no interface reporting how many cpuid configs contains in
> KVM_TDX_CAPABILITIES, QEMU chooses to try starting with a known number
> and abort when it exceeds KVM_MAX_CPUID_ENTRIES.
> 
> 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>
> ---
> Changes in v3:
> - rename __tdx_ioctl() to tdx_ioctl_internal()
> - Pass errp in get_tdx_capabilities();
> 
> changes in v2:
>   - Make the error message more clear;
> 
> changes in v1:
>   - start from nr_cpuid_configs = 6 for the loop;
>   - stop the loop when nr_cpuid_configs exceeds KVM_MAX_CPUID_ENTRIES;
> ---
>  target/i386/kvm/kvm.c      |   2 -
>  target/i386/kvm/kvm_i386.h |   2 +
>  target/i386/kvm/tdx.c      | 102 ++++++++++++++++++++++++++++++++++++-
>  3 files changed, 103 insertions(+), 3 deletions(-)
> 
> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
> index 7abcdebb1452..28e60c5ea4a7 100644
> --- a/target/i386/kvm/kvm.c
> +++ b/target/i386/kvm/kvm.c
> @@ -1687,8 +1687,6 @@ static int hyperv_init_vcpu(X86CPU *cpu)
>  
>  static Error *invtsc_mig_blocker;
>  
> -#define KVM_MAX_CPUID_ENTRIES  100
> -
>  static void kvm_init_xsave(CPUX86State *env)
>  {
>      if (has_xsave2) {
> diff --git a/target/i386/kvm/kvm_i386.h b/target/i386/kvm/kvm_i386.h
> index 55fb25fa8e2e..c3ef46a97a7b 100644
> --- a/target/i386/kvm/kvm_i386.h
> +++ b/target/i386/kvm/kvm_i386.h
> @@ -13,6 +13,8 @@
>  
>  #include "sysemu/kvm.h"
>  
> +#define KVM_MAX_CPUID_ENTRIES  100
> +
>  #ifdef CONFIG_KVM
>  
>  #define kvm_pit_in_kernel() \
> diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
> index 621a05beeb4e..cb0040187b27 100644
> --- a/target/i386/kvm/tdx.c
> +++ b/target/i386/kvm/tdx.c
> @@ -12,17 +12,117 @@
>   */
>  
>  #include "qemu/osdep.h"
> +#include "qemu/error-report.h"
>  #include "qapi/error.h"
>  #include "qom/object_interfaces.h"
> +#include "sysemu/kvm.h"
>  
>  #include "hw/i386/x86.h"
> +#include "kvm_i386.h"
>  #include "tdx.h"
>  
> +static struct kvm_tdx_capabilities *tdx_caps;
> +
> +enum tdx_ioctl_level{
> +    TDX_PLATFORM_IOCTL,
> +    TDX_VM_IOCTL,
> +    TDX_VCPU_IOCTL,
> +};
> +
> +static int tdx_ioctl_internal(void *state, enum tdx_ioctl_level level, int cmd_id,
> +                        __u32 flags, void *data)
> +{
> +    struct kvm_tdx_cmd tdx_cmd;

Add   ' = {}'  to initialize to all-zeros, avoiding the explicit
memset call

> +    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 flags, void *data)
> +{
> +    return tdx_ioctl_internal(NULL, TDX_PLATFORM_IOCTL, cmd_id, flags, data);
> +}
> +
> +static inline int tdx_vm_ioctl(int cmd_id, __u32 flags, void *data)
> +{
> +    return tdx_ioctl_internal(NULL, TDX_VM_IOCTL, cmd_id, flags, data);
> +}
> +
> +static inline int tdx_vcpu_ioctl(void *vcpu_fd, int cmd_id, __u32 flags,
> +                                 void *data)
> +{
> +    return  tdx_ioctl_internal(vcpu_fd, TDX_VCPU_IOCTL, cmd_id, flags, data);
> +}
> +
> +static int get_tdx_capabilities(Error **errp)
> +{
> +    struct kvm_tdx_capabilities *caps;
> +    /* 1st generation of TDX reports 6 cpuid configs */
> +    int nr_cpuid_configs = 6;
> +    size_t size;
> +    int r;
> +
> +    do {
> +        size = sizeof(struct kvm_tdx_capabilities) +
> +               nr_cpuid_configs * sizeof(struct kvm_tdx_cpuid_config);
> +        caps = g_malloc0(size);
> +        caps->nr_cpuid_configs = nr_cpuid_configs;
> +
> +        r = tdx_vm_ioctl(KVM_TDX_CAPABILITIES, 0, caps);
> +        if (r == -E2BIG) {
> +            g_free(caps);
> +            nr_cpuid_configs *= 2;
> +            if (nr_cpuid_configs > KVM_MAX_CPUID_ENTRIES) {
> +                error_setg(errp, "%s: KVM TDX seems broken that number of CPUID "
> +                           "entries in kvm_tdx_capabilities exceeds limit %d",
> +                           __func__, KVM_MAX_CPUID_ENTRIES);
> +                return r;
> +            }
> +        } else if (r < 0) {
> +            g_free(caps);
> +            error_setg_errno(errp, -r, "%s: KVM_TDX_CAPABILITIES failed", __func__);
> +            return r;
> +        }
> +    }
> +    while (r == -E2BIG);
> +
> +    tdx_caps = caps;
> +
> +    return 0;
> +}
> +
>  int tdx_kvm_init(MachineState *ms, Error **errp)
>  {
> +    int r = 0;
> +
>      ms->require_guest_memfd = true;
>  
> -    return 0;
> +    if (!tdx_caps) {
> +        r = get_tdx_capabilities(errp);
> +    }
> +
> +    return r;
>  }
>  
>  /* tdx guest */
> -- 
> 2.34.1
> 

With regards,
Daniel
Isaku Yamahata Nov. 17, 2023, 9:18 p.m. UTC | #2
On Wed, Nov 15, 2023 at 02:14:27AM -0500,
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.
> 
> Since there is no interface reporting how many cpuid configs contains in
> KVM_TDX_CAPABILITIES, QEMU chooses to try starting with a known number
> and abort when it exceeds KVM_MAX_CPUID_ENTRIES.
> 
> 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>
> ---
> Changes in v3:
> - rename __tdx_ioctl() to tdx_ioctl_internal()
> - Pass errp in get_tdx_capabilities();
> 
> changes in v2:
>   - Make the error message more clear;
> 
> changes in v1:
>   - start from nr_cpuid_configs = 6 for the loop;
>   - stop the loop when nr_cpuid_configs exceeds KVM_MAX_CPUID_ENTRIES;
> ---
>  target/i386/kvm/kvm.c      |   2 -
>  target/i386/kvm/kvm_i386.h |   2 +
>  target/i386/kvm/tdx.c      | 102 ++++++++++++++++++++++++++++++++++++-
>  3 files changed, 103 insertions(+), 3 deletions(-)
> 
> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
> index 7abcdebb1452..28e60c5ea4a7 100644
> --- a/target/i386/kvm/kvm.c
> +++ b/target/i386/kvm/kvm.c
> @@ -1687,8 +1687,6 @@ static int hyperv_init_vcpu(X86CPU *cpu)
>  
>  static Error *invtsc_mig_blocker;
>  
> -#define KVM_MAX_CPUID_ENTRIES  100
> -
>  static void kvm_init_xsave(CPUX86State *env)
>  {
>      if (has_xsave2) {
> diff --git a/target/i386/kvm/kvm_i386.h b/target/i386/kvm/kvm_i386.h
> index 55fb25fa8e2e..c3ef46a97a7b 100644
> --- a/target/i386/kvm/kvm_i386.h
> +++ b/target/i386/kvm/kvm_i386.h
> @@ -13,6 +13,8 @@
>  
>  #include "sysemu/kvm.h"
>  
> +#define KVM_MAX_CPUID_ENTRIES  100
> +
>  #ifdef CONFIG_KVM
>  
>  #define kvm_pit_in_kernel() \
> diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
> index 621a05beeb4e..cb0040187b27 100644
> --- a/target/i386/kvm/tdx.c
> +++ b/target/i386/kvm/tdx.c
> @@ -12,17 +12,117 @@
>   */
>  
>  #include "qemu/osdep.h"
> +#include "qemu/error-report.h"
>  #include "qapi/error.h"
>  #include "qom/object_interfaces.h"
> +#include "sysemu/kvm.h"
>  
>  #include "hw/i386/x86.h"
> +#include "kvm_i386.h"
>  #include "tdx.h"
>  
> +static struct kvm_tdx_capabilities *tdx_caps;
> +
> +enum tdx_ioctl_level{
> +    TDX_PLATFORM_IOCTL,
> +    TDX_VM_IOCTL,
> +    TDX_VCPU_IOCTL,
> +};
> +
> +static int tdx_ioctl_internal(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 flags, void *data)
> +{
> +    return tdx_ioctl_internal(NULL, TDX_PLATFORM_IOCTL, cmd_id, flags, data);
> +}
> +
> +static inline int tdx_vm_ioctl(int cmd_id, __u32 flags, void *data)
> +{
> +    return tdx_ioctl_internal(NULL, TDX_VM_IOCTL, cmd_id, flags, data);
> +}
> +
> +static inline int tdx_vcpu_ioctl(void *vcpu_fd, int cmd_id, __u32 flags,
> +                                 void *data)
> +{
> +    return  tdx_ioctl_internal(vcpu_fd, TDX_VCPU_IOCTL, cmd_id, flags, data);
> +}

As all of ioctl variants aren't used yet, we can split out them. An independent
patch to define ioctl functions.


> +
> +static int get_tdx_capabilities(Error **errp)
> +{
> +    struct kvm_tdx_capabilities *caps;
> +    /* 1st generation of TDX reports 6 cpuid configs */
> +    int nr_cpuid_configs = 6;
> +    size_t size;
> +    int r;
> +
> +    do {
> +        size = sizeof(struct kvm_tdx_capabilities) +
> +               nr_cpuid_configs * sizeof(struct kvm_tdx_cpuid_config);
> +        caps = g_malloc0(size);
> +        caps->nr_cpuid_configs = nr_cpuid_configs;
> +
> +        r = tdx_vm_ioctl(KVM_TDX_CAPABILITIES, 0, caps);
> +        if (r == -E2BIG) {
> +            g_free(caps);
> +            nr_cpuid_configs *= 2;

g_realloc()?  Maybe a matter of preference.

Other than this, it looks good to me.
Xiaoyao Li Dec. 7, 2023, 7:16 a.m. UTC | #3
On 11/18/2023 5:18 AM, Isaku Yamahata wrote:
> On Wed, Nov 15, 2023 at 02:14:27AM -0500,
> 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.
>>
>> Since there is no interface reporting how many cpuid configs contains in
>> KVM_TDX_CAPABILITIES, QEMU chooses to try starting with a known number
>> and abort when it exceeds KVM_MAX_CPUID_ENTRIES.
>>
>> 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>
>> ---
>> Changes in v3:
>> - rename __tdx_ioctl() to tdx_ioctl_internal()
>> - Pass errp in get_tdx_capabilities();
>>
>> changes in v2:
>>    - Make the error message more clear;
>>
>> changes in v1:
>>    - start from nr_cpuid_configs = 6 for the loop;
>>    - stop the loop when nr_cpuid_configs exceeds KVM_MAX_CPUID_ENTRIES;
>> ---
>>   target/i386/kvm/kvm.c      |   2 -
>>   target/i386/kvm/kvm_i386.h |   2 +
>>   target/i386/kvm/tdx.c      | 102 ++++++++++++++++++++++++++++++++++++-
>>   3 files changed, 103 insertions(+), 3 deletions(-)
>>
>> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
>> index 7abcdebb1452..28e60c5ea4a7 100644
>> --- a/target/i386/kvm/kvm.c
>> +++ b/target/i386/kvm/kvm.c
>> @@ -1687,8 +1687,6 @@ static int hyperv_init_vcpu(X86CPU *cpu)
>>   
>>   static Error *invtsc_mig_blocker;
>>   
>> -#define KVM_MAX_CPUID_ENTRIES  100
>> -
>>   static void kvm_init_xsave(CPUX86State *env)
>>   {
>>       if (has_xsave2) {
>> diff --git a/target/i386/kvm/kvm_i386.h b/target/i386/kvm/kvm_i386.h
>> index 55fb25fa8e2e..c3ef46a97a7b 100644
>> --- a/target/i386/kvm/kvm_i386.h
>> +++ b/target/i386/kvm/kvm_i386.h
>> @@ -13,6 +13,8 @@
>>   
>>   #include "sysemu/kvm.h"
>>   
>> +#define KVM_MAX_CPUID_ENTRIES  100
>> +
>>   #ifdef CONFIG_KVM
>>   
>>   #define kvm_pit_in_kernel() \
>> diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
>> index 621a05beeb4e..cb0040187b27 100644
>> --- a/target/i386/kvm/tdx.c
>> +++ b/target/i386/kvm/tdx.c
>> @@ -12,17 +12,117 @@
>>    */
>>   
>>   #include "qemu/osdep.h"
>> +#include "qemu/error-report.h"
>>   #include "qapi/error.h"
>>   #include "qom/object_interfaces.h"
>> +#include "sysemu/kvm.h"
>>   
>>   #include "hw/i386/x86.h"
>> +#include "kvm_i386.h"
>>   #include "tdx.h"
>>   
>> +static struct kvm_tdx_capabilities *tdx_caps;
>> +
>> +enum tdx_ioctl_level{
>> +    TDX_PLATFORM_IOCTL,
>> +    TDX_VM_IOCTL,
>> +    TDX_VCPU_IOCTL,
>> +};
>> +
>> +static int tdx_ioctl_internal(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 flags, void *data)
>> +{
>> +    return tdx_ioctl_internal(NULL, TDX_PLATFORM_IOCTL, cmd_id, flags, data);
>> +}
>> +
>> +static inline int tdx_vm_ioctl(int cmd_id, __u32 flags, void *data)
>> +{
>> +    return tdx_ioctl_internal(NULL, TDX_VM_IOCTL, cmd_id, flags, data);
>> +}
>> +
>> +static inline int tdx_vcpu_ioctl(void *vcpu_fd, int cmd_id, __u32 flags,
>> +                                 void *data)
>> +{
>> +    return  tdx_ioctl_internal(vcpu_fd, TDX_VCPU_IOCTL, cmd_id, flags, data);
>> +}
> 
> As all of ioctl variants aren't used yet, we can split out them. 

No. tdx_vm_ioctl() is used right below.

I can remove the tdx_platform_ioctl() because its sole user, 
KVM_TDX_CAPABILITIES, changed to vm scope.

> An independent
> patch to define ioctl functions.
> 
> 
>> +
>> +static int get_tdx_capabilities(Error **errp)
>> +{
>> +    struct kvm_tdx_capabilities *caps;
>> +    /* 1st generation of TDX reports 6 cpuid configs */
>> +    int nr_cpuid_configs = 6;
>> +    size_t size;
>> +    int r;
>> +
>> +    do {
>> +        size = sizeof(struct kvm_tdx_capabilities) +
>> +               nr_cpuid_configs * sizeof(struct kvm_tdx_cpuid_config);
>> +        caps = g_malloc0(size);
>> +        caps->nr_cpuid_configs = nr_cpuid_configs;
>> +
>> +        r = tdx_vm_ioctl(KVM_TDX_CAPABILITIES, 0, caps);
>> +        if (r == -E2BIG) {
>> +            g_free(caps);
>> +            nr_cpuid_configs *= 2;
> 
> g_realloc()?  Maybe a matter of preference.

I would like to keep the current code unless strong objection from 
maintainers.

> Other than this, it looks good to me.
Xiaoyao Li Dec. 7, 2023, 7:18 a.m. UTC | #4
On 11/15/2023 6:54 PM, Daniel P. Berrangé wrote:
>> +static int tdx_ioctl_internal(void *state, enum tdx_ioctl_level level, int cmd_id,
>> +                        __u32 flags, void *data)
>> +{
>> +    struct kvm_tdx_cmd tdx_cmd;
> Add   ' = {}'  to initialize to all-zeros, avoiding the explicit
> memset call

thanks for the suggestion. Will do it in the next version.
diff mbox series

Patch

diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 7abcdebb1452..28e60c5ea4a7 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -1687,8 +1687,6 @@  static int hyperv_init_vcpu(X86CPU *cpu)
 
 static Error *invtsc_mig_blocker;
 
-#define KVM_MAX_CPUID_ENTRIES  100
-
 static void kvm_init_xsave(CPUX86State *env)
 {
     if (has_xsave2) {
diff --git a/target/i386/kvm/kvm_i386.h b/target/i386/kvm/kvm_i386.h
index 55fb25fa8e2e..c3ef46a97a7b 100644
--- a/target/i386/kvm/kvm_i386.h
+++ b/target/i386/kvm/kvm_i386.h
@@ -13,6 +13,8 @@ 
 
 #include "sysemu/kvm.h"
 
+#define KVM_MAX_CPUID_ENTRIES  100
+
 #ifdef CONFIG_KVM
 
 #define kvm_pit_in_kernel() \
diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index 621a05beeb4e..cb0040187b27 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -12,17 +12,117 @@ 
  */
 
 #include "qemu/osdep.h"
+#include "qemu/error-report.h"
 #include "qapi/error.h"
 #include "qom/object_interfaces.h"
+#include "sysemu/kvm.h"
 
 #include "hw/i386/x86.h"
+#include "kvm_i386.h"
 #include "tdx.h"
 
+static struct kvm_tdx_capabilities *tdx_caps;
+
+enum tdx_ioctl_level{
+    TDX_PLATFORM_IOCTL,
+    TDX_VM_IOCTL,
+    TDX_VCPU_IOCTL,
+};
+
+static int tdx_ioctl_internal(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 flags, void *data)
+{
+    return tdx_ioctl_internal(NULL, TDX_PLATFORM_IOCTL, cmd_id, flags, data);
+}
+
+static inline int tdx_vm_ioctl(int cmd_id, __u32 flags, void *data)
+{
+    return tdx_ioctl_internal(NULL, TDX_VM_IOCTL, cmd_id, flags, data);
+}
+
+static inline int tdx_vcpu_ioctl(void *vcpu_fd, int cmd_id, __u32 flags,
+                                 void *data)
+{
+    return  tdx_ioctl_internal(vcpu_fd, TDX_VCPU_IOCTL, cmd_id, flags, data);
+}
+
+static int get_tdx_capabilities(Error **errp)
+{
+    struct kvm_tdx_capabilities *caps;
+    /* 1st generation of TDX reports 6 cpuid configs */
+    int nr_cpuid_configs = 6;
+    size_t size;
+    int r;
+
+    do {
+        size = sizeof(struct kvm_tdx_capabilities) +
+               nr_cpuid_configs * sizeof(struct kvm_tdx_cpuid_config);
+        caps = g_malloc0(size);
+        caps->nr_cpuid_configs = nr_cpuid_configs;
+
+        r = tdx_vm_ioctl(KVM_TDX_CAPABILITIES, 0, caps);
+        if (r == -E2BIG) {
+            g_free(caps);
+            nr_cpuid_configs *= 2;
+            if (nr_cpuid_configs > KVM_MAX_CPUID_ENTRIES) {
+                error_setg(errp, "%s: KVM TDX seems broken that number of CPUID "
+                           "entries in kvm_tdx_capabilities exceeds limit %d",
+                           __func__, KVM_MAX_CPUID_ENTRIES);
+                return r;
+            }
+        } else if (r < 0) {
+            g_free(caps);
+            error_setg_errno(errp, -r, "%s: KVM_TDX_CAPABILITIES failed", __func__);
+            return r;
+        }
+    }
+    while (r == -E2BIG);
+
+    tdx_caps = caps;
+
+    return 0;
+}
+
 int tdx_kvm_init(MachineState *ms, Error **errp)
 {
+    int r = 0;
+
     ms->require_guest_memfd = true;
 
-    return 0;
+    if (!tdx_caps) {
+        r = get_tdx_capabilities(errp);
+    }
+
+    return r;
 }
 
 /* tdx guest */