Commit fe9f1598 authored by Mukesh Rathor's avatar Mukesh Rathor Committed by Wei Liu
Browse files

x86/hyperv: Reserve 3 interrupt vectors used exclusively by MSHV 



MSVC compiler, used to compile the Microsoft Hypervisor, currently
has an assert intrinsic that uses interrupt vector 0x29 to create an
exception. This will cause hypervisor to then crash and collect core. As
such, if this interrupt number is assigned to a device by Linux and the
device generates it, hypervisor will crash. There are two other such
vectors hard coded in the hypervisor, 0x2C and 0x2D for debug purposes.

Fortunately, the three vectors are part of the kernel driver space and
that makes it feasible to reserve them early so they are not assigned
later.

Signed-off-by: default avatarMukesh Rathor <mrathor@linux.microsoft.com>
Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
parent f8e6343b

arch/x86/kernel/cpu/mshyperv.c

+25 −0
Original line number Diff line number Diff line
@@ -478,6 +478,28 @@ int hv_get_hypervisor_version(union hv_hypervisor_version_info *info) 
}

EXPORT_SYMBOL_GPL(hv_get_hypervisor_version);



/*

 * Reserved vectors hard coded in the hypervisor. If used outside, the hypervisor

 * will either crash or hang or attempt to break into debugger.

 */

static void hv_reserve_irq_vectors(void)

{

	#define HYPERV_DBG_FASTFAIL_VECTOR	0x29

	#define HYPERV_DBG_ASSERT_VECTOR	0x2C

	#define HYPERV_DBG_SERVICE_VECTOR	0x2D



	if (cpu_feature_enabled(X86_FEATURE_FRED))

		return;



	if (test_and_set_bit(HYPERV_DBG_ASSERT_VECTOR, system_vectors) ||

	    test_and_set_bit(HYPERV_DBG_SERVICE_VECTOR, system_vectors) ||

	    test_and_set_bit(HYPERV_DBG_FASTFAIL_VECTOR, system_vectors))

		BUG();



	pr_info("Hyper-V: reserve vectors: %d %d %d\n", HYPERV_DBG_ASSERT_VECTOR,

		HYPERV_DBG_SERVICE_VECTOR, HYPERV_DBG_FASTFAIL_VECTOR);

}



static void __init ms_hyperv_init_platform(void)

{

	int hv_max_functions_eax, eax;
@@ -510,6 +532,9 @@ static void __init ms_hyperv_init_platform(void) 


	hv_identify_partition_type();



	if (hv_root_partition())

		hv_reserve_irq_vectors();



	if (cc_platform_has(CC_ATTR_SNP_SECURE_AVIC))

		ms_hyperv.hints |= HV_DEPRECATING_AEOI_RECOMMENDED;