TD-Preserving updates request shutting down the existing TDX module.
During this shutdown, the module generates hand-off data, which captures
the module's states essential for preserving running TDs. The new TDX
module can utilize this hand-off data to establish its states.
Invoke the TDH_SYS_SHUTDOWN API on one CPU to perform the shutdown. This
API requires a hand-off module version. Use the module's own hand-off
version, as it is the highest version the module can produce and is more
likely to be compatible with new modules.
Changes to tdx_global_metadata.{hc} are auto-generated by following the
instructions detailed in [1], after adding the following section to the
tdx.py script:
"handoff": [
"MODULE_HV",
],
Add a check to ensure that module_hv is guarded by the TDX module's
support for TD-Preserving.
Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
Tested-by: Farrah Chen <farrah.chen@xxxxxxxxx>
Link: https://lore.kernel.org/kvm/20250226181453.2311849-12-pbonzini@xxxxxxxxxx/ [1]
---
arch/x86/include/asm/tdx_global_metadata.h | 5 +++++
arch/x86/virt/vmx/tdx/seamldr.c | 11 +++++++++++
arch/x86/virt/vmx/tdx/tdx.c | 18 ++++++++++++++++++
arch/x86/virt/vmx/tdx/tdx.h | 4 ++++
arch/x86/virt/vmx/tdx/tdx_global_metadata.c | 13 +++++++++++++
5 files changed, 51 insertions(+)
diff --git a/arch/x86/include/asm/tdx_global_metadata.h b/arch/x86/include/asm/tdx_global_metadata.h
index ce0370f4a5b9..a2011a3575ff 100644
--- a/arch/x86/include/asm/tdx_global_metadata.h
+++ b/arch/x86/include/asm/tdx_global_metadata.h
@@ -40,12 +40,17 @@ struct tdx_sys_info_td_conf {
u64 cpuid_config_values[128][2];
};
+struct tdx_sys_info_handoff {
+ u16 module_hv;
+};
+
struct tdx_sys_info {
struct tdx_sys_info_versions versions;
struct tdx_sys_info_features features;
struct tdx_sys_info_tdmr tdmr;
struct tdx_sys_info_td_ctrl td_ctrl;
struct tdx_sys_info_td_conf td_conf;
+ struct tdx_sys_info_handoff handoff;
};
#endif
diff --git a/arch/x86/virt/vmx/tdx/seamldr.c b/arch/x86/virt/vmx/tdx/seamldr.c
index 9d0d37a92bfd..11c0c5a93c32 100644
--- a/arch/x86/virt/vmx/tdx/seamldr.c
+++ b/arch/x86/virt/vmx/tdx/seamldr.c
@@ -241,6 +241,7 @@ static struct seamldr_params *init_seamldr_params(const u8 *data, u32 size)
enum tdp_state {
TDP_START,
+ TDP_SHUTDOWN,
TDP_DONE,
};
@@ -281,8 +282,12 @@ static void ack_state(void)
static int do_seamldr_install_module(void *params)
{
enum tdp_state newstate, curstate = TDP_START;
+ int cpu = smp_processor_id();
+ bool primary;
int ret = 0;
+ primary = !!(cpumask_first(cpu_online_mask) == cpu);
+
do {
/* Chill out and ensure we re-read tdp_data. */
cpu_relax();
@@ -291,6 +296,12 @@ static int do_seamldr_install_module(void *params)
if (newstate != curstate) {
curstate = newstate;
switch (curstate) {
+ case TDP_SHUTDOWN:
+ if (!primary)
+ break;
+
+ ret = tdx_module_shutdown();
+ break;
default:
break;
}
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 22ffc15b4299..fa6b3f1eb197 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -295,6 +295,11 @@ static int read_sys_metadata_field(u64 field_id, u64 *data)
return 0;
}
+static bool tdx_has_td_preserving(void)
+{
+ return tdx_sysinfo.features.tdx_features0 & TDX_FEATURES0_TD_PRESERVING;
+}
+
#include "tdx_global_metadata.c"
static int check_features(struct tdx_sys_info *sysinfo)
@@ -1341,6 +1346,19 @@ int tdx_enable(void)
}
EXPORT_SYMBOL_GPL(tdx_enable);
+int tdx_module_shutdown(void)
+{
+ struct tdx_module_args args = {};
+
+ /*
+ * Shut down TDX module and prepare handoff data for the next TDX module.
+ * Following a successful TDH_SYS_SHUTDOWN, further TDX module APIs will
+ * fail.
+ */
+ args.rcx = tdx_sysinfo.handoff.module_hv;
+ return seamcall_prerr(TDH_SYS_SHUTDOWN, &args);
+}
+
static bool is_pamt_page(unsigned long phys)
{
struct tdmr_info_list *tdmr_list = &tdx_tdmr_list;
diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
index 48c0a850c621..3830dee4da91 100644
--- a/arch/x86/virt/vmx/tdx/tdx.h
+++ b/arch/x86/virt/vmx/tdx/tdx.h
@@ -48,6 +48,7 @@
#define TDH_PHYMEM_PAGE_WBINVD 41
#define TDH_VP_WR 43
#define TDH_SYS_CONFIG 45
+#define TDH_SYS_SHUTDOWN 52
/*
* SEAMCALL leaf:
@@ -87,6 +88,7 @@ struct tdmr_info {
} __packed __aligned(TDMR_INFO_ALIGNMENT);
/* Bit definitions of TDX_FEATURES0 metadata field */
+#define TDX_FEATURES0_TD_PRESERVING BIT(1)
#define TDX_FEATURES0_NO_RBP_MOD BIT(18)
/*
@@ -122,4 +124,6 @@ struct tdmr_info_list {
int seamldr_prerr(u64 fn, struct tdx_module_args *args);
+int tdx_module_shutdown(void);
+
#endif
diff --git a/arch/x86/virt/vmx/tdx/tdx_global_metadata.c b/arch/x86/virt/vmx/tdx/tdx_global_metadata.c
index 088e5bff4025..a17cbb82e6b8 100644
--- a/arch/x86/virt/vmx/tdx/tdx_global_metadata.c
+++ b/arch/x86/virt/vmx/tdx/tdx_global_metadata.c
@@ -100,6 +100,18 @@ static int get_tdx_sys_info_td_conf(struct tdx_sys_info_td_conf *sysinfo_td_conf
return ret;
}
+static int get_tdx_sys_info_handoff(struct tdx_sys_info_handoff *sysinfo_handoff)
+{
+ int ret = 0;
+ u64 val;
+
+ if (!ret && tdx_has_td_preserving() &&
+ !(ret = read_sys_metadata_field(0x8900000100000000, &val)))
+ sysinfo_handoff->module_hv = val;
+
+ return ret;
+}
+
static int get_tdx_sys_info(struct tdx_sys_info *sysinfo)
{
int ret = 0;
@@ -109,6 +121,7 @@ static int get_tdx_sys_info(struct tdx_sys_info *sysinfo)
ret = ret ?: get_tdx_sys_info_tdmr(&sysinfo->tdmr);
ret = ret ?: get_tdx_sys_info_td_ctrl(&sysinfo->td_ctrl);
ret = ret ?: get_tdx_sys_info_td_conf(&sysinfo->td_conf);
+ ret = ret ?: get_tdx_sys_info_handoff(&sysinfo->handoff);
return ret;
}
--
2.47.1
