On Fri, Aug 18, 2023 at 05:49:49AM -0400, 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 <[email protected]>
> ---
> changes from v1:
> - Make the error message more clear;
>
> 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 | 93 ++++++++++++++++++++++++++++++++++++++
> 3 files changed, 95 insertions(+), 2 deletions(-)
>
> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
> index d6b988d6c2d1..ec5c07bffd38 100644
> --- a/target/i386/kvm/kvm.c
> +++ b/target/i386/kvm/kvm.c
> @@ -1751,8 +1751,6 @@ 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 ea3a5b174ac0..769eadbba56c 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..255c47a2a553 100644
> --- a/target/i386/kvm/tdx.c
> +++ b/target/i386/kvm/tdx.c
> @@ -12,14 +12,107 @@
> */
>
> #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(void *state, enum tdx_ioctl_level level, int cmd_id,
> + __u32 flags, void *data)
Names with an initial double underscore are reserved for us by the
platform implementation, so shouldn't be used in userspace app
code.
> +{
> + 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)
Pass in 'Error **errp'
> +{
> + struct kvm_tdx_capabilities *caps;
> + /* 1st generation of TDX reports 6 cpuid configs */
> + int nr_cpuid_configs = 6;
> + int r, size;
It is preferrable to use 'size_t' for memory allocation sizes.
> +
> + 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_report("KVM TDX seems broken that number of CPUID
> entries in kvm_tdx_capabilities exceeds limit");
Include the limit in the error message, so if we ever need to change
the limit, it'll be clear what limit the QEMU version was built with.
Also use error_setg(errp, ...);
> + exit(1);
Return -1
> + }
> + } else if (r < 0) {
> + g_free(caps);
> + error_report("KVM_TDX_CAPABILITIES failed: %s", strerror(-r));
Use error_setg_errno(errp, ...) instead of calling strerror yourself;
> + exit(1);
Return -1
> + }
> + }
> + while (r == -E2BIG);
> +
> + tdx_caps = caps;
Return 0
> +}
> +
> int tdx_kvm_init(MachineState *ms, Error **errp)
> {
> + if (!tdx_caps) {
> + get_tdx_capabilities();
Pass 'errp' into this method, and check return value for failure
> + }
> +
> return 0;
> }
>
> --
> 2.34.1
>
With regards,
Daniel
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