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Commit 99f85a28 authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: SVM: Remove port 80 passthrough 



KVM optimizes guest port 80 accesses by passthing them through to the host.
Some AMD machines die on port 80 writes, allowing the guest to hard-lock the
host.

Remove the port passthrough to avoid the problem.

Cc: stable@kernel.org
Reported-by: default avatarPiotr Jaroszyński <p.jaroszynski@gmail.com>
Tested-by: default avatarPiotr Jaroszyński <p.jaroszynski@gmail.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent e286e86e

arch/x86/kvm/svm.c

+0 −1
Original line number Diff line number Diff line
@@ -411,7 +411,6 @@ static __init int svm_hardware_setup(void) 


	iopm_va = page_address(iopm_pages);

	memset(iopm_va, 0xff, PAGE_SIZE * (1 << IOPM_ALLOC_ORDER));

	clear_bit(0x80, iopm_va); /* allow direct access to PC debug port */

	iopm_base = page_to_pfn(iopm_pages) << PAGE_SHIFT;



	if (boot_cpu_has(X86_FEATURE_NX))