Re: [PATCH v3 7/8] x86/virt/tdx: Reduce TDMR's reserved areas by using CMRs to find memory holes

From: Nikolay Borisov
Date: Fri Aug 30 2024 - 08:27:51 EST




On 27.08.24 г. 10:14 ч., Kai Huang wrote:
<snip>

[2] Convertible Memory Regions of the problematic platform:

virt/tdx: CMR: [0x100000, 0x6f800000)
virt/tdx: CMR: [0x100000000, 0x107a000000)
virt/tdx: CMR: [0x1080000000, 0x207c000000)
virt/tdx: CMR: [0x2080000000, 0x307c000000)
virt/tdx: CMR: [0x3080000000, 0x407c000000)

Fixes: dde3b60d572c9 ("x86/virt/tdx: Designate reserved areas for all TDMRs")
Signed-off-by: Kai Huang <kai.huang@xxxxxxxxx>
---

<snpi>

---
arch/x86/virt/vmx/tdx/tdx.c | 105 ++++++++++++++++++++++++++++++------
arch/x86/virt/vmx/tdx/tdx.h | 13 +++++
2 files changed, 102 insertions(+), 16 deletions(-)

diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 0fb673dd43ed..fa335ab1ae92 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -331,6 +331,72 @@ static int get_tdx_sys_info_version(struct tdx_sys_info_version *sysinfo_version
return ret;
}
+/* Update the @sysinfo_cmr->num_cmrs to trim tail empty CMRs */
+static void trim_empty_tail_cmrs(struct tdx_sys_info_cmr *sysinfo_cmr)
+{
+ int i;
+
+ for (i = 0; i < sysinfo_cmr->num_cmrs; i++) {
+ u64 cmr_base = sysinfo_cmr->cmr_base[i];
+ u64 cmr_size = sysinfo_cmr->cmr_size[i];
+
+ if (!cmr_size) {
+ WARN_ON_ONCE(cmr_base);
+ break;
+ }
+
+ /* TDX architecture: CMR must be 4KB aligned */
+ WARN_ON_ONCE(!PAGE_ALIGNED(cmr_base) ||
+ !PAGE_ALIGNED(cmr_size));
+ }
+
+ sysinfo_cmr->num_cmrs = i;
+}
+
+static int get_tdx_sys_info_cmr(struct tdx_sys_info_cmr *sysinfo_cmr)
+{
+ int i, ret = 0;
+
+#define TD_SYSINFO_MAP_CMR_INFO(_field_id, _member) \
+ TD_SYSINFO_MAP(_field_id, sysinfo_cmr, _member)
+
+ TD_SYSINFO_MAP_CMR_INFO(NUM_CMRS, num_cmrs);
+
+ if (ret)
+ return ret;
+
+ for (i = 0; i < sysinfo_cmr->num_cmrs; i++) {
+ TD_SYSINFO_MAP_CMR_INFO(CMR_BASE(i), cmr_base[i]);

Yeah, this is just golden, not only are you going through 3 levels of indirection to expand the TD_SYSINFO_MAP but you also top it with one final one MD_FIELD_ID_CMR_BASE(i). I'm fine with the CMR_BASE/SIZE macros, but the way you introduce 3 levels of macros just to avoid typing

TD_SYSINFO_MAP(foo, bar, zoo)

makes no sense.

<snip>