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

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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: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Suzuki K Poulose 2018-09-26 17:32:53 +01:00 committed by Marc Zyngier
parent 0f62f0e95b
commit 58b3efc820
2 changed files with 15 additions and 2 deletions
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7
arch/arm64/include/asm/stage2_pgtable.h
View File

@ -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))

10
arch/arm64/kvm/reset.c
View File

@ -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