Commit 86d1c55e authored by Punit Agrawal's avatar Punit Agrawal Committed by Marc Zyngier
Browse files

KVM: arm64: Support PUD hugepage in stage2_is_exec() 



In preparation for creating PUD hugepages at stage 2, add support for
detecting execute permissions on PUD page table entries. Faults due to
lack of execute permissions on page table entries is used to perform
i-cache invalidation on first execute.

Provide trivial implementations of arm32 helpers to allow sharing of
code.

Signed-off-by: default avatarPunit Agrawal <punit.agrawal@arm.com>
Reviewed-by: default avatarChristoffer Dall <christoffer.dall@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
[ Replaced BUG() => WARN_ON(1) in arm32 PUD helpers ]
Signed-off-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent 4ea5af53

arch/arm/include/asm/kvm_mmu.h

+6 −0
Original line number Diff line number Diff line
@@ -102,6 +102,12 @@ static inline bool kvm_s2pud_readonly(pud_t *pud) 
	return false;

}



static inline bool kvm_s2pud_exec(pud_t *pud)

{

	WARN_ON(1);

	return false;

}



static inline pte_t kvm_s2pte_mkwrite(pte_t pte)

{

	pte_val(pte) |= L_PTE_S2_RDWR;

arch/arm64/include/asm/kvm_mmu.h

+5 −0
Original line number Diff line number Diff line
@@ -261,6 +261,11 @@ static inline bool kvm_s2pud_readonly(pud_t *pudp) 
	return kvm_s2pte_readonly((pte_t *)pudp);

}



static inline bool kvm_s2pud_exec(pud_t *pudp)

{

	return !(READ_ONCE(pud_val(*pudp)) & PUD_S2_XN);

}



#define hyp_pte_table_empty(ptep) kvm_page_empty(ptep)



#ifdef __PAGETABLE_PMD_FOLDED

arch/arm64/include/asm/pgtable-hwdef.h

+2 −0
Original line number Diff line number Diff line
@@ -193,6 +193,8 @@ 
#define PMD_S2_RDWR		(_AT(pmdval_t, 3) << 6)   /* HAP[2:1] */

#define PMD_S2_XN		(_AT(pmdval_t, 2) << 53)  /* XN[1:0] */



#define PUD_S2_XN		(_AT(pudval_t, 2) << 53)  /* XN[1:0] */



/*

 * Memory Attribute override for Stage-2 (MemAttr[3:0])

 */

virt/kvm/arm/mmu.c

+48 −5
Original line number Diff line number Diff line
@@ -1083,22 +1083,65 @@ static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache 
	return 0;

}



static bool stage2_is_exec(struct kvm *kvm, phys_addr_t addr)

/*

 * stage2_get_leaf_entry - walk the stage2 VM page tables and return

 * true if a valid and present leaf-entry is found. A pointer to the

 * leaf-entry is returned in the appropriate level variable - pudpp,

 * pmdpp, ptepp.

 */

static bool stage2_get_leaf_entry(struct kvm *kvm, phys_addr_t addr,

				  pud_t **pudpp, pmd_t **pmdpp, pte_t **ptepp)

{

	pud_t *pudp;

	pmd_t *pmdp;

	pte_t *ptep;



	pmdp = stage2_get_pmd(kvm, NULL, addr);

	*pudpp = NULL;

	*pmdpp = NULL;

	*ptepp = NULL;



	pudp = stage2_get_pud(kvm, NULL, addr);

	if (!pudp || stage2_pud_none(kvm, *pudp) || !stage2_pud_present(kvm, *pudp))

		return false;



	if (stage2_pud_huge(kvm, *pudp)) {

		*pudpp = pudp;

		return true;

	}



	pmdp = stage2_pmd_offset(kvm, pudp, addr);

	if (!pmdp || pmd_none(*pmdp) || !pmd_present(*pmdp))

		return false;



	if (pmd_thp_or_huge(*pmdp))

		return kvm_s2pmd_exec(pmdp);

	if (pmd_thp_or_huge(*pmdp)) {

		*pmdpp = pmdp;

		return true;

	}



	ptep = pte_offset_kernel(pmdp, addr);

	if (!ptep || pte_none(*ptep) || !pte_present(*ptep))

		return false;



	*ptepp = ptep;

	return true;

}



static bool stage2_is_exec(struct kvm *kvm, phys_addr_t addr)

{

	pud_t *pudp;

	pmd_t *pmdp;

	pte_t *ptep;

	bool found;



	found = stage2_get_leaf_entry(kvm, addr, &pudp, &pmdp, &ptep);

	if (!found)

		return false;



	if (pudp)

		return kvm_s2pud_exec(pudp);

	else if (pmdp)

		return kvm_s2pmd_exec(pmdp);

	else

		return kvm_s2pte_exec(ptep);

}

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