linux-kernel - [RFC PATCH v5 26/45] x86/virt/tdx: Enhance tdh_mem_page

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Message-ID: <20260129011517.3545883-27-seanjc@google.com>
Date: Wed, 28 Jan 2026 17:14:58 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Thomas Gleixner <tglx@...nel.org>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	Kiryl Shutsemau <kas@...nel.org>, Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-coco@...ts.linux.dev, 
	kvm@...r.kernel.org, Kai Huang <kai.huang@...el.com>, 
	Rick Edgecombe <rick.p.edgecombe@...el.com>, Yan Zhao <yan.y.zhao@...el.com>, 
	Vishal Annapurve <vannapurve@...gle.com>, Ackerley Tng <ackerleytng@...gle.com>, 
	Sagi Shahar <sagis@...gle.com>, Binbin Wu <binbin.wu@...ux.intel.com>, 
	Xiaoyao Li <xiaoyao.li@...el.com>, Isaku Yamahata <isaku.yamahata@...el.com>
Subject: [RFC PATCH v5 26/45] x86/virt/tdx: Enhance tdh_mem_page_aug() to
 support huge pages

From: Yan Zhao <yan.y.zhao@...el.com>

Enhance the SEAMCALL wrapper tdh_mem_page_aug() to support huge pages.

The SEAMCALL TDH_MEM_PAGE_AUG currently supports adding physical memory to
the S-EPT up to 2MB in size.

While keeping the "level" parameter in the tdh_mem_page_aug() wrapper to
allow callers to specify the physical memory size, introduce the parameters
"folio" and "start_idx" to specify the physical memory starting from the
page at "start_idx" within the "folio". The specified physical memory must
be fully contained within a single folio.

Invoke tdx_clflush_page() for each 4KB segment of the physical memory being
added. tdx_clflush_page() performs CLFLUSH operations conservatively to
prevent dirty cache lines from writing back later and corrupting TD memory.

Signed-off-by: Xiaoyao Li <xiaoyao.li@...el.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
[sean: remove the page+folio assumptions]
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/virt/vmx/tdx/tdx.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 85c31ed9b9d1..37776ea56eb7 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -1756,9 +1756,13 @@ u64 tdh_mem_page_aug(struct tdx_td *td, u64 gpa, enum pg_level level, u64 pfn,
 		.rdx = tdx_tdr_pa(td),
 		.r8 = PFN_PHYS(pfn),
 	};
+	unsigned long npages = page_level_size(level) / PAGE_SIZE;
+	unsigned long i;
 	u64 ret;
 
-	tdx_clflush_pfn(pfn);
+	for (i = 0; i < npages; i++)
+		tdx_clflush_pfn(pfn + i);
+
 	ret = seamcall_ret(TDH_MEM_PAGE_AUG, &args);
 
 	*ext_err1 = args.rcx;
-- 
2.53.0.rc1.217.geba53bf80e-goog