[PATCH v7 4/6] x86/tdx: Forcefully disable legacy PIC for TDX guests

[Kuppuswamy Sathyanarayanan]

From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>

Disable the legacy PIC (8259) for TDX guests as the PIC cannot be
supported by the VMM. TDX Module does not allow direct IRQ injection,
and using posted interrupt style delivery requires the guest to EOI
the IRQ, which diverges from the legacy PIC behavior.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Reviewed-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
---

Changes since v6:
 * None

 arch/x86/kernel/tdx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c
index 203deb57c4c9..987dc3ee5bbf 100644
--- a/arch/x86/kernel/tdx.c
+++ b/arch/x86/kernel/tdx.c
@@ -7,6 +7,7 @@
 #include <linux/cpuhotplug.h>
 
 #include <asm/tdx.h>
+#include <asm/i8259.h>
 #include <asm/vmx.h>
 #include <asm/insn.h>
 #include <asm/insn-eval.h>
@@ -464,6 +465,8 @@ void __init tdx_early_init(void)
 	pv_ops.irq.safe_halt = tdx_safe_halt;
 	pv_ops.irq.halt = tdx_halt;
 
+	legacy_pic = &null_legacy_pic;
+
 	cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "tdx:cpu_hotplug",
 			  NULL, tdx_cpu_offline_prepare);
 
-- 
2.25.1