On 5/27/2022 2:48 AM, Isaku Yamahata wrote:
On Thu, May 26, 2022 at 03:33:10PM +0800,
Xiaoyao Li <xiaoyao.li@xxxxxxxxx> wrote:
On 5/24/2022 3:37 PM, Gerd Hoffmann wrote:
I think all this can be simplified, by
(1) Change the existing entry to cover the accepted ram range.
(2) If there is room before the accepted ram range add a
TDX_RAM_UNACCEPTED entry for that.
(3) If there is room after the accepted ram range add a
TDX_RAM_UNACCEPTED entry for that.
I implement as below. Please help review.
+static int tdx_accept_ram_range(uint64_t address, uint64_t length)
+{
+ uint64_t head_start, tail_start, head_length, tail_length;
+ uint64_t tmp_address, tmp_length;
+ TdxRamEntry *e;
+ int i;
+
+ for (i = 0; i < tdx_guest->nr_ram_entries; i++) {
+ e = &tdx_guest->ram_entries[i];
+
+ if (address + length < e->address ||
+ e->address + e->length < address) {
+ continue;
+ }
+
+ /*
+ * The to-be-accepted ram range must be fully contained by one
+ * RAM entries
+ */
+ if (e->address > address ||
+ e->address + e->length < address + length) {
+ return -EINVAL;
+ }
+
+ if (e->type == TDX_RAM_ADDED) {
+ return -EINVAL;
+ }
+
+ tmp_address = e->address;
+ tmp_length = e->length;
+
+ e->address = address;
+ e->length = length;
+ e->type = TDX_RAM_ADDED;
+
+ head_length = address - tmp_address;
+ if (head_length > 0) {
+ head_start = e->address;
+ tdx_add_ram_entry(head_start, head_length, TDX_RAM_UNACCEPTED);
tdx_add_ram_entry() increments tdx_guest->nr_ram_entries. I think it's worth
for comments why this is safe regarding to this for-loop.
The for-loop is to find the valid existing RAM entry (from E820 table).
It will update the RAM entry and increment tdx_guest->nr_ram_entries
when the initial RAM entry needs to be split. However, once find, the
for-loop is certainly stopped since it returns unconditionally.
