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

Xiaoyao Li
2023-11-15T07:17:36Z

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);
+}
+
+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