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ANDROID: KVM: arm64: Provide a helper to compute the size of stage-2 PGDs

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We will soon need to donate memory to the hypervisor in protected mode
when creating guest VMs. The amount of memory to be donated will depend on
the size of the (potentially concatenated) stage-2 PGD for that guest,
among other things. To prepare the ground for this donation, introduce a
helper in the KVM page-table library allowing to compute the size of a
stage-2 PGD given a VTCR.

Signed-off-by: Quentin Perret <qperret@google.com>
Bug: 209580772
Change-Id: I266f85d17415e72eb574afdb1d8b622d87b9fcc3
Signed-off-by: Will Deacon <willdeacon@google.com>
This commit is contained in:
Quentin Perret
2021-10-08 11:08:02 +01:00
committed by Will Deacon
parent 233f0df2b1
commit f42a0f7153
2 changed files with 17 additions and 0 deletions
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8
arch/arm64/include/asm/kvm_pgtable.h
View File

@@ -288,6 +288,14 @@ u64 kvm_pgtable_hyp_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size);
*/
u64 kvm_get_vtcr(u64 mmfr0, u64 mmfr1, u32 phys_shift);
/*
* kvm_pgtable_stage2_pgd_size() - Helper to compute size of a stage-2 PGD
* @vtcr: Content of the VTCR register.
*
* Return: the size (in bytes) of the stage-2 PGD
*/
size_t kvm_pgtable_stage2_pgd_size(u64 vtcr);
/**
* __kvm_pgtable_stage2_init() - Initialise a guest stage-2 page-table.
* @pgt: Uninitialised page-table structure to initialise.

9
arch/arm64/kvm/hyp/pgtable.c
View File

@@ -1209,6 +1209,15 @@ int __kvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_s2_mmu *mmu,
return 0;
}
size_t kvm_pgtable_stage2_pgd_size(u64 vtcr)
{
u32 ia_bits = VTCR_EL2_IPA(vtcr);
u32 sl0 = FIELD_GET(VTCR_EL2_SL0_MASK, vtcr);
u32 start_level = VTCR_EL2_TGRAN_SL0_BASE - sl0;
return kvm_pgd_pages(ia_bits, start_level) * PAGE_SIZE;
}
static int stage2_free_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
enum kvm_pgtable_walk_flags flag,
void * const arg)