[PATCH v9 16/18] x86/virt/tdx: Initialize all TDMRs

Kai Huang
2023-02-13T12:04:00Z

After the global KeyID has been configured on all packages, initialize
all TDMRs to make all TDX-usable memory regions that are passed to the
TDX module become usable.

This is the last step of initializing the TDX module.

Initializing TDMRs can be time consuming on large memory systems as it
involves initializing all metadata entries for all pages that can be
used by TDX guests. Initializing different TDMRs can be parallelized.
For now to keep it simple, just initialize all TDMRs one by one. It can
be enhanced in the future.

Signed-off-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com>
---

v8 -> v9:
- Improved changlog to explain why initializing TDMRs can take long
time (Dave).
- Improved comments around 'next-to-initialize' address (Dave).

v7 -> v8: (Dave)
- Changelog:
- explicitly call out this is the last step of TDX module initialization.
- Trimed down changelog by removing SEAMCALL name and details.
- Removed/trimmed down unnecessary comments.
- Other changes due to 'struct tdmr_info_list'.

v6 -> v7:
- Removed need_resched() check. -- Andi.

---
arch/x86/virt/vmx/tdx/tdx.c | 60 ++++++++++++++++++++++++++++++++-----
arch/x86/virt/vmx/tdx/tdx.h | 1 +
2 files changed, 53 insertions(+), 8 deletions(-)

diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index ff6f2c9d9838..c291fbd29bb0 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -1086,6 +1086,56 @@ static int config_global_keyid(void)
return ret;
}

+static int init_tdmr(struct tdmr_info *tdmr)
+{
+ u64 next;
+
+ /*
+ * Initializing a TDMR can be time consuming. To avoid long
+ * SEAMCALLs, the TDX module may only initialize a part of the
+ * TDMR in each call.
+ */
+ do {
+ struct tdx_module_output out;
+ int ret;
+
+ /* All 0's are unused parameters, they mean nothing. */
+ ret = seamcall(TDH_SYS_TDMR_INIT, tdmr->base, 0, 0, 0, NULL,
+ &out);
+ if (ret)
+ return ret;
+ /*
+ * RDX contains 'next-to-initialize' address if
+ * TDH.SYS.TDMR.INIT did not fully complete and
+ * should be retried.
+ */
+ next = out.rdx;
+ cond_resched();
+ /* Keep making SEAMCALLs until the TDMR is done */
+ } while (next < tdmr->base + tdmr->size);
+
+ return 0;
+}
+
+static int init_tdmrs(struct tdmr_info_list *tdmr_list)
+{
+ int i;
+
+ /*
+ * This operation is costly. It can be parallelized,
+ * but keep it simple for now.
+ */
+ for (i = 0; i < tdmr_list->nr_consumed_tdmrs; i++) {
+ int ret;
+
+ ret = init_tdmr(tdmr_entry(tdmr_list, i));
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
static int init_tdx_module(void)
{
static DECLARE_PADDED_STRUCT(tdsysinfo_struct, tdsysinfo,
@@ -1170,15 +1220,9 @@ static int init_tdx_module(void)
if (ret)
goto out_free_pamts;

- /*
- * TODO:
- *
- * - Initialize all TDMRs.
- *
- * Return error before all steps are done.
- */
+ /* Initialize TDMRs to complete the TDX module initialization */
+ ret = init_tdmrs(&tdx_tdmr_list);

- ret = -EINVAL;
out_free_pamts:
if (ret) {
/*
diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
index ca4e2edbf4bc..4e312c7f9553 100644
--- a/arch/x86/virt/vmx/tdx/tdx.h
+++ b/arch/x86/virt/vmx/tdx/tdx.h
@@ -18,6 +18,7 @@
*/
#define TDH_SYS_KEY_CONFIG 31
#define TDH_SYS_INFO 32
+#define TDH_SYS_TDMR_INIT 36
#define TDH_SYS_CONFIG 45

struct cmr_info {
--
2.39.1