diff options
Diffstat (limited to 'arch/x86/hyperv/hv_vtl.c')
| -rw-r--r-- | arch/x86/hyperv/hv_vtl.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c index 3f4e20d7b724..13242ed8ff16 100644 --- a/arch/x86/hyperv/hv_vtl.c +++ b/arch/x86/hyperv/hv_vtl.c @@ -12,6 +12,7 @@ #include <asm/i8259.h> #include <asm/mshyperv.h> #include <asm/realmode.h> +#include <asm/reboot.h> #include <../kernel/smpboot.h> extern struct boot_params boot_params; @@ -22,6 +23,36 @@ static bool __init hv_vtl_msi_ext_dest_id(void) return true; } +/* + * The `native_machine_emergency_restart` function from `reboot.c` writes + * to the physical address 0x472 to indicate the type of reboot for the + * firmware. We cannot have that in VSM as the memory composition might + * be more generic, and such write effectively corrupts the memory thus + * making diagnostics harder at the very least. + */ +static void __noreturn hv_vtl_emergency_restart(void) +{ + /* + * Cause a triple fault and the immediate reset. Here the code does not run + * on the top of any firmware, whereby cannot reach out to its services. + * The inifinite loop is for the improbable case that the triple fault does + * not work and have to preserve the state intact for debugging. + */ + for (;;) { + idt_invalidate(); + __asm__ __volatile__("int3"); + } +} + +/* + * The only way to restart in the VTL mode is to triple fault as the kernel runs + * as firmware. + */ +static void __noreturn hv_vtl_restart(char __maybe_unused *cmd) +{ + hv_vtl_emergency_restart(); +} + void __init hv_vtl_init_platform(void) { pr_info("Linux runs in Hyper-V Virtual Trust Level\n"); @@ -236,6 +267,9 @@ static int hv_vtl_wakeup_secondary_cpu(u32 apicid, unsigned long start_eip) int __init hv_vtl_early_init(void) { + machine_ops.emergency_restart = hv_vtl_emergency_restart; + machine_ops.restart = hv_vtl_restart; + /* * `boot_cpu_has` returns the runtime feature support, * and here is the earliest it can be used. |