Commit b09763da authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
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KVM: x86/mmu: Add module param to disable MMIO caching (for testing) 



Add a module param to disable MMIO caching so that it's possible to test
the related flows without access to the necessary hardware.  Using shadow
paging with 64-bit KVM and 52 bits of physical address space must disable
MMIO caching as there are no reserved bits to be had.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20210225204749.1512652-12-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 8120337a

arch/x86/kvm/mmu/spte.c

+6 −0
Original line number Diff line number Diff line
@@ -17,6 +17,9 @@ 


#include <asm/e820/api.h>



static bool __read_mostly enable_mmio_caching = true;

module_param_named(mmio_caching, enable_mmio_caching, bool, 0444);



u64 __read_mostly shadow_nx_mask;

u64 __read_mostly shadow_x_mask; /* mutual exclusive with nx_mask */

u64 __read_mostly shadow_user_mask;
@@ -251,6 +254,9 @@ void kvm_mmu_set_mmio_spte_mask(u64 mmio_value, u64 mmio_mask, u64 access_mask) 
	BUG_ON((u64)(unsigned)access_mask != access_mask);

	WARN_ON(mmio_value & shadow_nonpresent_or_rsvd_lower_gfn_mask);



	if (!enable_mmio_caching)

		mmio_value = 0;



	/*

	 * Disable MMIO caching if the MMIO value collides with the bits that

	 * are used to hold the relocated GFN when the L1TF mitigation is