[PATCH v1 06/40] i386/tdx: Get tdx_capabilities via KVM_TDX_CAPABILITIES

Xiaoyao Li
2022-08-02T07:48:54Z

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 from RFC v4:
- 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 | 92 ++++++++++++++++++++++++++++++++++++++
3 files changed, 94 insertions(+), 2 deletions(-)

diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 335f87e6cc59..9e30fa9f4eb5 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -1704,8 +1704,6 @@ 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 b434feaa6b1d..6b24ab2a7813 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
+
#define kvm_apic_in_kernel() (kvm_irqchip_in_kernel())

#ifdef CONFIG_KVM
diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index 77e33ae01147..89f81f7d7082 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -14,12 +14,104 @@
#include "qemu/osdep.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(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(NULL, TDX_PLATFORM_IOCTL, cmd_id, flags, data);
+}
+
+static inline int tdx_vm_ioctl(int cmd_id, __u32 flags, void *data)
+{
+ return __tdx_ioctl(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(vcpu_fd, TDX_VCPU_IOCTL, cmd_id, flags, data);
+}
+
+static void get_tdx_capabilities(void)
+{
+ struct kvm_tdx_capabilities *caps;
+ /* 1st generation of TDX reports 6 cpuid configs */
+ int nr_cpuid_configs = 6;
+ int r, size;
+
+ 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_platform_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_report("KVM TDX seems broken");
+ exit(1);
+ }
+ } else if (r < 0) {
+ g_free(caps);
+ 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