The kernel configures TDX usable memory regions to the TDX module via
an array of "TD Memory Region" (TDMR). Each TDMR entry (TDMR_INFO)
contains the information of the base/size of a memory region, the
base/size of the associated Physical Address Metadata Table (PAMT) and
a list of reserved areas in the region.
Create a number of TDMRs according to the verified e820 RAM entries.
As the first step only set up the base/size information for each TDMR.
TDMR must be 1G aligned and the size must be in 1G granularity. This
implies that one TDMR could cover multiple e820 RAM entries. If a RAM
entry spans the 1GB boundary and the former part is already covered by
the previous TDMR, just create a new TDMR for the latter part.
TDX only supports a limited number of TDMRs (currently 64). Abort the
TDMR construction process when the number of TDMRs exceeds this
limitation.
Signed-off-by: Kai Huang <kai.huang@xxxxxxxxx>
---
arch/x86/virt/vmx/tdx.c | 138 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 138 insertions(+)
diff --git a/arch/x86/virt/vmx/tdx.c b/arch/x86/virt/vmx/tdx.c
index 0780ec71651b..fe83cf9ac2f9 100644
--- a/arch/x86/virt/vmx/tdx.c
+++ b/arch/x86/virt/vmx/tdx.c
@@ -53,6 +53,18 @@
((u32)(((_keyid_part) & 0xffffffffull) + 1))
#define TDX_KEYID_NUM(_keyid_part) ((u32)((_keyid_part) >> 32))
+/* TDMR must be 1gb aligned */
+#define TDMR_ALIGNMENT BIT_ULL(30)
+#define TDMR_PFN_ALIGNMENT (TDMR_ALIGNMENT >> PAGE_SHIFT)
+
+/* Align up and down the address to TDMR boundary */
+#define TDMR_ALIGN_DOWN(_addr) ALIGN_DOWN((_addr), TDMR_ALIGNMENT)
+#define TDMR_ALIGN_UP(_addr) ALIGN((_addr), TDMR_ALIGNMENT)
+
+/* TDMR's start and end address */
+#define TDMR_START(_tdmr) ((_tdmr)->base)
+#define TDMR_END(_tdmr) ((_tdmr)->base + (_tdmr)->size)
+
/*
* TDX module status during initialization
*/
@@ -732,6 +744,44 @@ static int e820_check_against_cmrs(void)
return 0;
}
+/* The starting offset of reserved areas within TDMR_INFO */
+#define TDMR_RSVD_START 64
+
+static struct tdmr_info *__alloc_tdmr(void)
+{
+ int tdmr_sz;
+
+ /*
+ * TDMR_INFO's actual size depends on maximum number of reserved
+ * areas that one TDMR supports.
+ */
+ tdmr_sz = TDMR_RSVD_START + tdx_sysinfo.max_reserved_per_tdmr *
+ sizeof(struct tdmr_reserved_area);
+
+ /*
+ * TDX requires TDMR_INFO to be 512 aligned. Always align up
+ * TDMR_INFO size to 512 so the memory allocated via kzalloc()
+ * can meet the alignment requirement.
+ */
+ tdmr_sz = ALIGN(tdmr_sz, TDMR_INFO_ALIGNMENT);
+
+ return kzalloc(tdmr_sz, GFP_KERNEL);
+}
+
+/* Create a new TDMR at given index in the TDMR array */
+static struct tdmr_info *alloc_tdmr(struct tdmr_info **tdmr_array, int idx)
+{
+ struct tdmr_info *tdmr;
+
+ if (WARN_ON_ONCE(tdmr_array[idx]))
+ return NULL;
+
+ tdmr = __alloc_tdmr();
+ tdmr_array[idx] = tdmr;
+
+ return tdmr;
+}
+
static void free_tdmrs(struct tdmr_info **tdmr_array, int tdmr_num)
{
int i;
@@ -745,6 +795,89 @@ static void free_tdmrs(struct tdmr_info **tdmr_array, int tdmr_num)
}
}
+/*
+ * Create TDMRs to cover all RAM entries in e820_table. The created
+ * TDMRs are saved to @tdmr_array and @tdmr_num is set to the actual
+ * number of TDMRs. All entries in @tdmr_array must be initially NULL.
+ */
+static int create_tdmrs(struct tdmr_info **tdmr_array, int *tdmr_num)
+{
+ struct tdmr_info *tdmr;
+ u64 start, end;
+ int i, tdmr_idx;
+ int ret = 0;
+
+ tdmr_idx = 0;
+ tdmr = alloc_tdmr(tdmr_array, 0);
+ if (!tdmr)
+ return -ENOMEM;
+ /*
+ * Loop over all RAM entries in e820 and create TDMRs to cover
+ * them. To keep it simple, always try to use one TDMR to cover
+ * one RAM entry.
+ */
+ e820_for_each_mem(e820_table, i, start, end) {
+ start = TDMR_ALIGN_DOWN(start);
+ end = TDMR_ALIGN_UP(end);
+
+ /*
+ * If the current TDMR's size hasn't been initialized, it
+ * is a new allocated TDMR to cover the new RAM entry.
+ * Otherwise the current TDMR already covers the previous
+ * RAM entry. In the latter case, check whether the
+ * current RAM entry has been fully or partially covered
+ * by the current TDMR, since TDMR is 1G aligned.
+ */
+ if (tdmr->size) {
+ /*
+ * Loop to next RAM entry if the current entry
+ * is already fully covered by the current TDMR.
+ */
+ if (end <= TDMR_END(tdmr))
+ continue;
+
+ /*
+ * If part of current RAM entry has already been
+ * covered by current TDMR, skip the already
+ * covered part.
+ */
+ if (start < TDMR_END(tdmr))
+ start = TDMR_END(tdmr);
+
+ /*
+ * Create a new TDMR to cover the current RAM
+ * entry, or the remaining part of it.
+ */
+ tdmr_idx++;
+ if (tdmr_idx >= tdx_sysinfo.max_tdmrs) {
+ ret = -E2BIG;
+ goto err;
+ }
+ tdmr = alloc_tdmr(tdmr_array, tdmr_idx);
+ if (!tdmr) {
+ ret = -ENOMEM;
+ goto err;
+ }
+ }
+
+ tdmr->base = start;
+ tdmr->size = end - start;
+ }
+
+ /* @tdmr_idx is always the index of last valid TDMR. */
+ *tdmr_num = tdmr_idx + 1;
+
+ return 0;
+err:
+ /*
+ * Clean up already allocated TDMRs in case of error. @tdmr_idx
+ * indicates the last TDMR that wasn't created successfully,
+ * therefore only needs to free @tdmr_idx TDMRs.
+ */
+ free_tdmrs(tdmr_array, tdmr_idx);
+ return ret;
+}
+
static int construct_tdmrs(struct tdmr_info **tdmr_array, int *tdmr_num)
{
int ret;
@@ -753,8 +886,13 @@ static int construct_tdmrs(struct tdmr_info **tdmr_array, int *tdmr_num)
if (ret)
goto err;
+ ret = create_tdmrs(tdmr_array, tdmr_num);
+ if (ret)
+ goto err;
+
/* Return -EFAULT until constructing TDMRs is done */
ret = -EFAULT;
+ free_tdmrs(tdmr_array, *tdmr_num);
err:
return ret;
}
--
2.33.1
