x86/virt/tdx: Designate reserved areas for all TDMRs

As the last step of constructing TDMRs, populate reserved areas for all
TDMRs.  Cover all memory holes and PAMTs with a TMDR reserved area.

[ dhansen: trim down chagnelog ]
Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Yuan Yao <yuan.yao@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/all/20231208170740.53979-12-dave.hansen%40intel.com

arch/x86/virt/vmx/tdx/tdx.c

@@ -23,6 +23,7 @@
 #include <linux/sizes.h>
 #include <linux/pfn.h>
 #include <linux/align.h>
+#include <linux/sort.h>
 #include <asm/msr-index.h>
 #include <asm/msr.h>
 #include <asm/cpufeature.h>
@@ -662,6 +663,207 @@ static unsigned long tdmrs_count_pamt_kb(struct tdmr_info_list *tdmr_list)
 	return pamt_size / 1024;
 }
 
+static int tdmr_add_rsvd_area(struct tdmr_info *tdmr, int *p_idx, u64 addr,
+			      u64 size, u16 max_reserved_per_tdmr)
+{
+	struct tdmr_reserved_area *rsvd_areas = tdmr->reserved_areas;
+	int idx = *p_idx;
+
+	/* Reserved area must be 4K aligned in offset and size */
+	if (WARN_ON(addr & ~PAGE_MASK || size & ~PAGE_MASK))
+		return -EINVAL;
+
+	if (idx >= max_reserved_per_tdmr) {
+		pr_warn("initialization failed: TDMR [0x%llx, 0x%llx): reserved areas exhausted.\n",
+				tdmr->base, tdmr_end(tdmr));
+		return -ENOSPC;
+	}
+
+	/*
+	 * Consume one reserved area per call.  Make no effort to
+	 * optimize or reduce the number of reserved areas which are
+	 * consumed by contiguous reserved areas, for instance.
+	 */
+	rsvd_areas[idx].offset = addr - tdmr->base;
+	rsvd_areas[idx].size = size;
+
+	*p_idx = idx + 1;
+
+	return 0;
+}
+
+/*
+ * Go through @tmb_list to find holes between memory areas.  If any of
+ * those holes fall within @tdmr, set up a TDMR reserved area to cover
+ * the hole.
+ */
+static int tdmr_populate_rsvd_holes(struct list_head *tmb_list,
+				    struct tdmr_info *tdmr,
+				    int *rsvd_idx,
+				    u16 max_reserved_per_tdmr)
+{
+	struct tdx_memblock *tmb;
+	u64 prev_end;
+	int ret;
+
+	/*
+	 * Start looking for reserved blocks at the
+	 * beginning of the TDMR.
+	 */
+	prev_end = tdmr->base;
+	list_for_each_entry(tmb, tmb_list, list) {
+		u64 start, end;
+
+		start = PFN_PHYS(tmb->start_pfn);
+		end   = PFN_PHYS(tmb->end_pfn);
+
+		/* Break if this region is after the TDMR */
+		if (start >= tdmr_end(tdmr))
+			break;
+
+		/* Exclude regions before this TDMR */
+		if (end < tdmr->base)
+			continue;
+
+		/*
+		 * Skip over memory areas that
+		 * have already been dealt with.
+		 */
+		if (start <= prev_end) {
+			prev_end = end;
+			continue;
+		}
+
+		/* Add the hole before this region */
+		ret = tdmr_add_rsvd_area(tdmr, rsvd_idx, prev_end,
+				start - prev_end,
+				max_reserved_per_tdmr);
+		if (ret)
+			return ret;
+
+		prev_end = end;
+	}
+
+	/* Add the hole after the last region if it exists. */
+	if (prev_end < tdmr_end(tdmr)) {
+		ret = tdmr_add_rsvd_area(tdmr, rsvd_idx, prev_end,
+				tdmr_end(tdmr) - prev_end,
+				max_reserved_per_tdmr);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * Go through @tdmr_list to find all PAMTs.  If any of those PAMTs
+ * overlaps with @tdmr, set up a TDMR reserved area to cover the
+ * overlapping part.
+ */
+static int tdmr_populate_rsvd_pamts(struct tdmr_info_list *tdmr_list,
+				    struct tdmr_info *tdmr,
+				    int *rsvd_idx,
+				    u16 max_reserved_per_tdmr)
+{
+	int i, ret;
+
+	for (i = 0; i < tdmr_list->nr_consumed_tdmrs; i++) {
+		struct tdmr_info *tmp = tdmr_entry(tdmr_list, i);
+		unsigned long pamt_base, pamt_size, pamt_end;
+
+		tdmr_get_pamt(tmp, &pamt_base, &pamt_size);
+		/* Each TDMR must already have PAMT allocated */
+		WARN_ON_ONCE(!pamt_size || !pamt_base);
+
+		pamt_end = pamt_base + pamt_size;
+		/* Skip PAMTs outside of the given TDMR */
+		if ((pamt_end <= tdmr->base) ||
+				(pamt_base >= tdmr_end(tdmr)))
+			continue;
+
+		/* Only mark the part within the TDMR as reserved */
+		if (pamt_base < tdmr->base)
+			pamt_base = tdmr->base;
+		if (pamt_end > tdmr_end(tdmr))
+			pamt_end = tdmr_end(tdmr);
+
+		ret = tdmr_add_rsvd_area(tdmr, rsvd_idx, pamt_base,
+				pamt_end - pamt_base,
+				max_reserved_per_tdmr);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/* Compare function called by sort() for TDMR reserved areas */
+static int rsvd_area_cmp_func(const void *a, const void *b)
+{
+	struct tdmr_reserved_area *r1 = (struct tdmr_reserved_area *)a;
+	struct tdmr_reserved_area *r2 = (struct tdmr_reserved_area *)b;
+
+	if (r1->offset + r1->size <= r2->offset)
+		return -1;
+	if (r1->offset >= r2->offset + r2->size)
+		return 1;
+
+	/* Reserved areas cannot overlap.  The caller must guarantee. */
+	WARN_ON_ONCE(1);
+	return -1;
+}
+
+/*
+ * Populate reserved areas for the given @tdmr, including memory holes
+ * (via @tmb_list) and PAMTs (via @tdmr_list).
+ */
+static int tdmr_populate_rsvd_areas(struct tdmr_info *tdmr,
+				    struct list_head *tmb_list,
+				    struct tdmr_info_list *tdmr_list,
+				    u16 max_reserved_per_tdmr)
+{
+	int ret, rsvd_idx = 0;
+
+	ret = tdmr_populate_rsvd_holes(tmb_list, tdmr, &rsvd_idx,
+			max_reserved_per_tdmr);
+	if (ret)
+		return ret;
+
+	ret = tdmr_populate_rsvd_pamts(tdmr_list, tdmr, &rsvd_idx,
+			max_reserved_per_tdmr);
+	if (ret)
+		return ret;
+
+	/* TDX requires reserved areas listed in address ascending order */
+	sort(tdmr->reserved_areas, rsvd_idx, sizeof(struct tdmr_reserved_area),
+			rsvd_area_cmp_func, NULL);
+
+	return 0;
+}
+
+/*
+ * Populate reserved areas for all TDMRs in @tdmr_list, including memory
+ * holes (via @tmb_list) and PAMTs.
+ */
+static int tdmrs_populate_rsvd_areas_all(struct tdmr_info_list *tdmr_list,
+					 struct list_head *tmb_list,
+					 u16 max_reserved_per_tdmr)
+{
+	int i;
+
+	for (i = 0; i < tdmr_list->nr_consumed_tdmrs; i++) {
+		int ret;
+
+		ret = tdmr_populate_rsvd_areas(tdmr_entry(tdmr_list, i),
+				tmb_list, tdmr_list, max_reserved_per_tdmr);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
 /*
  * Construct a list of TDMRs on the preallocated space in @tdmr_list
  * to cover all TDX memory regions in @tmb_list based on the TDX module
@@ -681,14 +883,13 @@ static int construct_tdmrs(struct list_head *tmb_list,
 			tdmr_sysinfo->pamt_entry_size);
 	if (ret)
 		return ret;
-	/*
-	 * TODO:
-	 *
-	 *  - Designate reserved areas for each TDMR.
-	 *
-	 * Return -EINVAL until constructing TDMRs is done
-	 */
-	return -EINVAL;
+
+	ret = tdmrs_populate_rsvd_areas_all(tdmr_list, tmb_list,
+			tdmr_sysinfo->max_reserved_per_tdmr);
+	if (ret)
+		tdmrs_free_pamt_all(tdmr_list);
+
+	return ret;
 }
 
 static int init_tdx_module(void)