Re: [PATCH] x86/virt/tdx: Warn on !4K level in tdh_mem_page_aug()

[Sean Christopherson <seanjc@google.com>]

On Tue, Aug 25, 2026, Yan Zhao wrote:
> Add a warning on a !4K level to loudly flag the unexpected condition when
> callers pass in a level > 4K before tdh_mem_page_aug() supports huge pages.
> 
> The warning makes the unexpected condition more obvious since the SEAMCALL
> TDH_MEM_PAGE_AUG does not necessarily fail when the level is above 4K,
> while tdh_mem_page_aug() only flushes the cache for a 4K page before huge
> page support is added.

If the only problem is the lack of CLFLUSH coverage, why not simply fix the
bug?  The changelog spends more effort justifying not fixing a bug than it would
take to fix the bug.

diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 42df8ea464c4..1a83857eb7e6 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -1628,9 +1628,9 @@ static void tdx_clflush_page(struct page *page)
 	clflush_cache_range(page_to_virt(page), PAGE_SIZE);
 }
 
-static void tdx_clflush_pfn(kvm_pfn_t pfn)
+static void tdx_clflush_pfn(kvm_pfn_t pfn, enum pg_level level)
 {
-	clflush_cache_range(__va(PFN_PHYS(pfn)), PAGE_SIZE);
+	clflush_cache_range(__va(PFN_PHYS(pfn)), page_level_size(level));
 }
 
 static int pg_level_to_tdx_sept_level(enum pg_level level)
@@ -1670,7 +1670,7 @@ u64 tdh_mem_page_add(struct tdx_td *td, u64 gpa, kvm_pfn_t pfn, struct page *sou
 	};
 	u64 ret;
 
-	tdx_clflush_pfn(pfn);
+	tdx_clflush_pfn(pfn, PG_LEVEL_4K);
 	ret = seamcall_ret(TDH_MEM_PAGE_ADD, &args);
 
 	*ext_err1 = args.rcx;
@@ -1722,7 +1722,7 @@ u64 tdh_mem_page_aug(struct tdx_td *td, u64 gpa, enum pg_level level,
 	};
 	u64 ret;
 
-	tdx_clflush_pfn(pfn);
+	tdx_clflush_pfn(pfn, level);
 	ret = seamcall_ret(TDH_MEM_PAGE_AUG, &args);
 
 	*ext_err1 = args.rcx;