linux-kernel - [PATCH v3 11/26] x86/virt/seamldr: Block TDX Module updates if any CPU is offline

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Message-ID: <20260123145645.90444-12-chao.gao@intel.com>
Date: Fri, 23 Jan 2026 06:55:19 -0800
From: Chao Gao <chao.gao@...el.com>
To: linux-coco@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org,
	x86@...nel.org
Cc: reinette.chatre@...el.com,
	ira.weiny@...el.com,
	kai.huang@...el.com,
	dan.j.williams@...el.com,
	yilun.xu@...ux.intel.com,
	sagis@...gle.com,
	vannapurve@...gle.com,
	paulmck@...nel.org,
	nik.borisov@...e.com,
	zhenzhong.duan@...el.com,
	seanjc@...gle.com,
	rick.p.edgecombe@...el.com,
	kas@...nel.org,
	dave.hansen@...ux.intel.com,
	vishal.l.verma@...el.com,
	Chao Gao <chao.gao@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH v3 11/26] x86/virt/seamldr: Block TDX Module updates if any CPU is offline

P-SEAMLDR requires every CPU to call the SEAMLDR.INSTALL SEAMCALL during
updates.  So, every CPU should be online.

Check if all CPUs are online and abort the update if any CPU is offline at
the very beginning. Without this check, P-SEAMLDR will report failure at a
later phase where the old TDX module is gone and TDs have to be killed.

Signed-off-by: Chao Gao <chao.gao@...el.com>
---
 arch/x86/virt/vmx/tdx/seamldr.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/virt/vmx/tdx/seamldr.c b/arch/x86/virt/vmx/tdx/seamldr.c
index af7a6621e5e0..88388aa0fb5f 100644
--- a/arch/x86/virt/vmx/tdx/seamldr.c
+++ b/arch/x86/virt/vmx/tdx/seamldr.c
@@ -6,6 +6,8 @@
  */
 #define pr_fmt(fmt)	"seamldr: " fmt
 
+#include <linux/cpuhplock.h>
+#include <linux/cpumask.h>
 #include <linux/irqflags.h>
 #include <linux/mm.h>
 #include <linux/types.h>
@@ -84,6 +86,12 @@ int seamldr_install_module(const u8 *data, u32 size)
 	if (!is_vmalloc_addr(data))
 		return -EINVAL;
 
+	guard(cpus_read_lock)();
+	if (!cpumask_equal(cpu_online_mask, cpu_present_mask)) {
+		pr_err("Cannot update TDX module if any CPU is offline\n");
+		return -EBUSY;
+	}
+
 	/* TODO: Update TDX Module here */
 	return 0;
 }
-- 
2.47.3