From 80200341197a799fe39da4e9da61bde4d23ec7ec Mon Sep 17 00:00:00 2001 From: Yunhong Jiang Date: Wed, 4 Mar 2026 15:41:20 -0800 Subject: [PATCH] x86/hyperv/vtl: Mark the wakeup mailbox page as private The current code maps MMIO devices as shared (decrypted) by default in a confidential computing VM. In a TDX environment, secondary CPUs are booted using the Multiprocessor Wakeup Structure defined in the ACPI specification. The virtual firmware and the operating system function in the guest context, without intervention from the VMM. Map the physical memory of the mailbox as private. Use the is_private_mmio() callback. Signed-off-by: Yunhong Jiang Signed-off-by: Ricardo Neri Signed-off-by: Dexuan Cui --- arch/x86/hyperv/hv_vtl.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c index b94fffa673128..1e2f5b3ea7720 100644 --- a/arch/x86/hyperv/hv_vtl.c +++ b/arch/x86/hyperv/hv_vtl.c @@ -6,6 +6,9 @@ * Saurabh Sengar */ +#include + +#include #include #include #include @@ -59,6 +62,18 @@ static void __noreturn hv_vtl_restart(char __maybe_unused *cmd) hv_vtl_emergency_restart(); } +static inline bool within_page(u64 addr, u64 start) +{ + return addr >= start && addr < (start + PAGE_SIZE); +} + +static bool hv_vtl_is_private_mmio_tdx(u64 addr) +{ + u64 mb_addr = acpi_get_mp_wakeup_mailbox_paddr(); + + return mb_addr && within_page(addr, mb_addr); +} + void __init hv_vtl_init_platform(void) { /* @@ -71,6 +86,8 @@ void __init hv_vtl_init_platform(void) /* There is no paravisor present if we are here. */ if (hv_isolation_type_tdx()) { x86_init.resources.realmode_limit = SZ_4G; + x86_platform.hyper.is_private_mmio = hv_vtl_is_private_mmio_tdx; + } else { x86_platform.realmode_reserve = x86_init_noop; x86_platform.realmode_init = x86_init_noop; -- 2.47.3