Re: [PATCH v13 17/22] x86/kexec: Flush cache of TDX private memory

[Edgecombe, Rick P]

On Sat, 2023-08-26 at 00:14 +1200, Kai Huang wrote:
> There are two problems in terms of using kexec() to boot to a new
> kernel
> when the old kernel has enabled TDX: 1) Part of the memory pages are
> still TDX private pages; 2) There might be dirty cachelines
> associated
> with TDX private pages.

Does TDX support hibernate? I'm wondering about two potential problems:
1. Reading/writing private pages from the direct map on save/restore
2. The seam module needing to be re-inited (the tdx_enable() stuff)

If that's the case you could have something like the below to just
block it when TDX could be in use:
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 2b4a946a6ff5..3b1b7202452d 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -84,7 +84,8 @@ bool hibernation_available(void)
 {
        return nohibernate == 0 &&
                !security_locked_down(LOCKDOWN_HIBERNATION) &&
-               !secretmem_active() && !cxl_mem_active();
+               !secretmem_active() && !cxl_mem_active() &&
+               !platform_tdx_enabled();
 }
 
 /**

Or maybe better, it could check tdx_module_status? But there is no way
to read that variable from hibernate.