linux-kernel - [RFC PATCH 02/21] x86/virt/tdx: Enhance tdh_mem_page

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Message-ID: <20250424030428.32687-1-yan.y.zhao@intel.com>
Date: Thu, 24 Apr 2025 11:04:28 +0800
From: Yan Zhao <yan.y.zhao@...el.com>
To: pbonzini@...hat.com,
	seanjc@...gle.com
Cc: linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org,
	x86@...nel.org,
	rick.p.edgecombe@...el.com,
	dave.hansen@...el.com,
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	pgonda@...gle.com,
	zhiquan1.li@...el.com,
	fan.du@...el.com,
	jun.miao@...el.com,
	ira.weiny@...el.com,
	isaku.yamahata@...el.com,
	xiaoyao.li@...el.com,
	binbin.wu@...ux.intel.com,
	chao.p.peng@...el.com,
	Yan Zhao <yan.y.zhao@...el.com>
Subject: [RFC PATCH 02/21] x86/virt/tdx: Enhance tdh_mem_page_aug() to support huge pages

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

Verify the validity of the level and ensure that the mapping range is fully
contained within the page folio.

As a conservative solution, perform CLFLUSH on all pages to be mapped into
the TD before invoking the SEAMCALL TDH_MEM_PAGE_AUG. This ensures that any
dirty cache lines do not write back later and clobber 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>
---
 arch/x86/virt/vmx/tdx/tdx.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index f5e2a937c1e7..a66d501b5677 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -1595,9 +1595,18 @@ u64 tdh_mem_page_aug(struct tdx_td *td, u64 gpa, int level, struct page *page, u
 		.rdx = tdx_tdr_pa(td),
 		.r8 = page_to_phys(page),
 	};
+	unsigned long nr_pages = 1 << (level * 9);
+	struct folio *folio = page_folio(page);
+	unsigned long idx = 0;
 	u64 ret;
 
-	tdx_clflush_page(page);
+	if (!(level >= TDX_PS_4K && level < TDX_PS_NR) ||
+	    (folio_page_idx(folio, page) + nr_pages > folio_nr_pages(folio)))
+		return -EINVAL;
+
+	while (nr_pages--)
+		tdx_clflush_page(nth_page(page, idx++));
+
 	ret = seamcall_ret(TDH_MEM_PAGE_AUG, &args);
 
 	*ext_err1 = args.rcx;
-- 
2.43.2