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Commit 58b3efc8 authored by Suzuki K Poulose's avatar Suzuki K Poulose Committed by Marc Zyngier
Browse files

kvm: arm64: Limit the minimum number of page table levels 



Since we are about to remove the lower limit on the IPA size,
make sure that we do not go to 1 level page table (e.g, with
32bit IPA on 64K host with concatenation) to avoid splitting
the host PMD huge pages at stage2.

Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Christoffer Dall <cdall@kernel.org>
Reviewed-by: default avatarEric Auger <eric.auger@redhat.com>
Signed-off-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent 0f62f0e9

arch/arm64/include/asm/stage2_pgtable.h

+6 −1
Original line number Diff line number Diff line
@@ -72,8 +72,13 @@ 
/*

 * The number of PTRS across all concatenated stage2 tables given by the

 * number of bits resolved at the initial level.

 * If we force more levels than necessary, we may have (stage2_pgdir_shift > IPA),

 * in which case, stage2_pgd_ptrs will have one entry.

 */

#define __s2_pgd_ptrs(ipa, lvls)	(1 << ((ipa) - pt_levels_pgdir_shift((lvls))))

#define pgd_ptrs_shift(ipa, pgdir_shift)	\

	((ipa) > (pgdir_shift) ? ((ipa) - (pgdir_shift)) : 0)

#define __s2_pgd_ptrs(ipa, lvls)		\

	(1 << (pgd_ptrs_shift((ipa), pt_levels_pgdir_shift(lvls))))

#define __s2_pgd_size(ipa, lvls)	(__s2_pgd_ptrs((ipa), (lvls)) * sizeof(pgd_t))



#define stage2_pgd_ptrs(kvm)		__s2_pgd_ptrs(kvm_phys_shift(kvm), kvm_stage2_levels(kvm))

arch/arm64/kvm/reset.c

+9 −1
Original line number Diff line number Diff line
@@ -190,6 +190,7 @@ int kvm_arm_config_vm(struct kvm *kvm, unsigned long type) 
{

	u64 vtcr = VTCR_EL2_FLAGS;

	u32 parange, phys_shift;

	u8 lvls;



	if (type)

		return -EINVAL;
@@ -203,7 +204,14 @@ int kvm_arm_config_vm(struct kvm *kvm, unsigned long type) 
	if (phys_shift > KVM_PHYS_SHIFT)

		phys_shift = KVM_PHYS_SHIFT;

	vtcr |= VTCR_EL2_T0SZ(phys_shift);

	vtcr |= VTCR_EL2_LVLS_TO_SL0(stage2_pgtable_levels(phys_shift));

	/*

	 * Use a minimum 2 level page table to prevent splitting

	 * host PMD huge pages at stage2.

	 */

	lvls = stage2_pgtable_levels(phys_shift);

	if (lvls < 2)

		lvls = 2;

	vtcr |= VTCR_EL2_LVLS_TO_SL0(lvls);



	/*

	 * Enable the Hardware Access Flag management, unconditionally