linux-kernel - [PATCH v2 8/9] x86/hyperv: Set realmode

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Message-Id: <20240823232327.2408869-9-yunhong.jiang@linux.intel.com>
Date: Fri, 23 Aug 2024 16:23:26 -0700
From: Yunhong Jiang <yunhong.jiang@...ux.intel.com>
To: tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	x86@...nel.org,
	hpa@...or.com,
	robh@...nel.org,
	krzk+dt@...nel.org,
	conor+dt@...nel.org,
	kys@...rosoft.com,
	haiyangz@...rosoft.com,
	wei.liu@...nel.org,
	decui@...rosoft.com,
	rafael@...nel.org,
	lenb@...nel.org,
	kirill.shutemov@...ux.intel.com,
	yunhong.jiang@...ux.intel.com
Cc: linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-hyperv@...r.kernel.org,
	linux-acpi@...r.kernel.org
Subject: [PATCH v2 8/9] x86/hyperv: Set realmode_limit to 4G for VTL2 TDX guest

The VTL2 TDX guest may have no sub-1M memory available, but it needs to
invoke trampoline_start64 to wake up the APs through the wakeup mailbox
mechanism. Set realmode_limit to 4G for the VTL2 TDX guest, so that
reserve_real_mode allocae memory under 4G.

Signed-off-by: Yunhong Jiang <yunhong.jiang@...ux.intel.com>
---
 arch/x86/hyperv/hv_vtl.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c
index e5aa2688cdd0..5829aac74f80 100644
--- a/arch/x86/hyperv/hv_vtl.c
+++ b/arch/x86/hyperv/hv_vtl.c
@@ -40,11 +40,15 @@ void __init hv_vtl_init_platform(void)
 {
 	pr_info("Linux runs in Hyper-V Virtual Trust Level\n");
 
-	if (hv_isolation_type_tdx())
+	if (hv_isolation_type_tdx()) {
 		x86_platform.hyper.is_private_mmio = hv_is_private_mmio_tdx;
-	x86_platform.realmode_reserve = x86_init_noop;
-	x86_platform.realmode_init = x86_init_noop;
-	real_mode_header = &hv_vtl_real_mode_header;
+		x86_init.resources.realmode_limit = SZ_4G;
+		x86_init.resources.reserve_bios = 0;
+	} else {
+		x86_platform.realmode_reserve = x86_init_noop;
+		x86_platform.realmode_init = x86_init_noop;
+		real_mode_header = &hv_vtl_real_mode_header;
+	}
 	x86_init.irqs.pre_vector_init = x86_init_noop;
 	x86_init.timers.timer_init = x86_init_noop;
 
-- 
2.25.1