| Message ID | 20250503191515.24041-11-ricardo.neri-calderon@linux.intel.com |
|---|---|
| State | New |
| Headers | show |
| Series | x86/hyperv/hv_vtl: Use a wakeup mailbox to boot secondary CPUs | expand |
From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> Sent: Saturday, May 3, 2025 12:15 PM > > From: Yunhong Jiang <yunhong.jiang@linux.intel.com> > > The hypervisor is an untrusted entity for TDX guests. It cannot be used > to boot secondary CPUs - neither via hypercalls not the INIT assert, > de-assert plus Start-Up IPI messages. > > Instead, the platform virtual firmware boots the secondary CPUs and > puts them in a state to transfer control to the kernel. This mechanism uses > the wakeup mailbox described in the Multiprocessor Wakeup Structure of the > ACPI specification. The entry point to the kernel is trampoline_start64. > > Allocate and setup the trampoline using the default x86_platform callbacks. > > The platform firmware configures the secondary CPUs in long mode. It is no > longer necessary to locate the trampoline under 1MB memory. After handoff > from firmware, the trampoline code switches briefly to 32-bit addressing > mode, which has an addressing limit of 4GB. Set the upper bound of the > trampoline memory accordingly. > > Signed-off-by: Yunhong Jiang <yunhong.jiang@linux.intel.com> > Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> > --- > Changes since v2: > - Added a note regarding there is no need to check for a present > paravisor. > - Edited commit message for clarity. > > Changes since v1: > - Dropped the function hv_reserve_real_mode(). Instead, used the new > members realmode_limit and reserve_bios members of x86_init to > set the upper bound of the trampoline memory. (Thomas) > --- > arch/x86/hyperv/hv_vtl.c | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c > index 6bd183ee484f..8b497c8292d3 100644 > --- a/arch/x86/hyperv/hv_vtl.c > +++ b/arch/x86/hyperv/hv_vtl.c > @@ -58,9 +58,14 @@ void __init hv_vtl_init_platform(void) > { > pr_info("Linux runs in Hyper-V Virtual Trust Level\n"); > > - x86_platform.realmode_reserve = x86_init_noop; > - x86_platform.realmode_init = x86_init_noop; > - real_mode_header = &hv_vtl_real_mode_header; > + /* There is no paravisor present if we are here. */ > + if (hv_isolation_type_tdx()) { > + x86_init.resources.realmode_limit = SZ_4G; > + } 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; > x86_init.resources.probe_roms = x86_init_noop; > -- > 2.43.0 Reviewed-by: Michael Kelley <mhklinux@outlook.com>
diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c index 6bd183ee484f..8b497c8292d3 100644 --- a/arch/x86/hyperv/hv_vtl.c +++ b/arch/x86/hyperv/hv_vtl.c @@ -58,9 +58,14 @@ void __init hv_vtl_init_platform(void) { pr_info("Linux runs in Hyper-V Virtual Trust Level\n"); - x86_platform.realmode_reserve = x86_init_noop; - x86_platform.realmode_init = x86_init_noop; - real_mode_header = &hv_vtl_real_mode_header; + /* There is no paravisor present if we are here. */ + if (hv_isolation_type_tdx()) { + x86_init.resources.realmode_limit = SZ_4G; + } 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; x86_init.resources.probe_roms = x86_init_noop;