x86/hyperv: add noop functions to x86_init mpparse functions

[ Upstream commit 9e2d0c336524706fb327e9b87477f5f3337ad7a6 ]

Hyper-V can run VMs at different privilege "levels" known as Virtual
Trust Levels (VTL). Sometimes, it chooses to run two different VMs
at different levels but they share some of their address space. In
such setups VTL2 (higher level VM) has visibility of all of the
VTL0 (level 0) memory space.

When the CONFIG_X86_MPPARSE is enabled for VTL2, the VTL2 kernel
performs a search within the low memory to locate MP tables. However,
in systems where VTL0 manages the low memory and may contain valid
tables, this scanning can result in incorrect MP table information
being provided to the VTL2 kernel, mistakenly considering VTL0's MP
table as its own

Add noop functions to avoid MP parse scan by VTL2.

Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/1687537688-5397-1-git-send-email-ssengar@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c
index 85d38b9f35861b65eafe3b4323bfae2f99e5fab3..db5d2ea39fc0d2389613b4cba8291af52d64c2f5 100644 (file)
--- a/arch/x86/hyperv/hv_vtl.c
+++ b/arch/x86/hyperv/hv_vtl.c
@@ -25,6 +25,10 @@ void __init hv_vtl_init_platform(void)
        x86_init.irqs.pre_vector_init = x86_init_noop;
        x86_init.timers.timer_init = x86_init_noop;
 
+       /* Avoid searching for BIOS MP tables */
+       x86_init.mpparse.find_smp_config = x86_init_noop;
+       x86_init.mpparse.get_smp_config = x86_init_uint_noop;
+
        x86_platform.get_wallclock = get_rtc_noop;
        x86_platform.set_wallclock = set_rtc_noop;
        x86_platform.get_nmi_reason = hv_get_nmi_reason;