Commit 4505e9b6 authored by Quentin Perret's avatar Quentin Perret Committed by Marc Zyngier
Browse files

KVM: arm64: Allow populating software bits 

Introduce infrastructure allowing to manipulate software bits in stage-1
and stage-2 page-tables using additional entries in the kvm_pgtable_prot
enum.

This is heavily inspired by Marc's implementation of a similar feature
in the NV patch series, but adapted to allow stage-1 changes as well:

  https://lore.kernel.org/kvmarm/20210510165920.1913477-56-maz@kernel.org/



Suggested-by: default avatarMarc Zyngier <maz@kernel.org>
Signed-off-by: default avatarQuentin Perret <qperret@google.com>
Reviewed-by: default avatarFuad Tabba <tabba@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210809152448.1810400-12-qperret@google.com
parent 56513119

arch/arm64/include/asm/kvm_pgtable.h

+11 −1
Original line number Diff line number Diff line
@@ -121,6 +121,10 @@ enum kvm_pgtable_stage2_flags { 
 * @KVM_PGTABLE_PROT_W:		Write permission.

 * @KVM_PGTABLE_PROT_R:		Read permission.

 * @KVM_PGTABLE_PROT_DEVICE:	Device attributes.

 * @KVM_PGTABLE_PROT_SW0:	Software bit 0.

 * @KVM_PGTABLE_PROT_SW1:	Software bit 1.

 * @KVM_PGTABLE_PROT_SW2:	Software bit 2.

 * @KVM_PGTABLE_PROT_SW3:	Software bit 3.

 */

enum kvm_pgtable_prot {

	KVM_PGTABLE_PROT_X			= BIT(0),
@@ -128,6 +132,11 @@ enum kvm_pgtable_prot { 
	KVM_PGTABLE_PROT_R			= BIT(2),



	KVM_PGTABLE_PROT_DEVICE			= BIT(3),



	KVM_PGTABLE_PROT_SW0			= BIT(55),

	KVM_PGTABLE_PROT_SW1			= BIT(56),

	KVM_PGTABLE_PROT_SW2			= BIT(57),

	KVM_PGTABLE_PROT_SW3			= BIT(58),

};



#define KVM_PGTABLE_PROT_RW	(KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W)
@@ -420,7 +429,8 @@ kvm_pte_t kvm_pgtable_stage2_mkold(struct kvm_pgtable *pgt, u64 addr); 
 * If there is a valid, leaf page-table entry used to translate @addr, then

 * relax the permissions in that entry according to the read, write and

 * execute permissions specified by @prot. No permissions are removed, and

 * TLB invalidation is performed after updating the entry.

 * TLB invalidation is performed after updating the entry. Software bits cannot

 * be set or cleared using kvm_pgtable_stage2_relax_perms().

 *

 * Return: 0 on success, negative error code on failure.

 */

arch/arm64/kvm/hyp/pgtable.c

+5 −0
Original line number Diff line number Diff line
@@ -357,6 +357,7 @@ static int hyp_set_prot_attr(enum kvm_pgtable_prot prot, kvm_pte_t *ptep) 
	attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S1_AP, ap);

	attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S1_SH, sh);

	attr |= KVM_PTE_LEAF_ATTR_LO_S1_AF;

	attr |= prot & KVM_PTE_LEAF_ATTR_HI_SW;

	*ptep = attr;



	return 0;
@@ -558,6 +559,7 @@ static int stage2_set_prot_attr(struct kvm_pgtable *pgt, enum kvm_pgtable_prot p 


	attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S2_SH, sh);

	attr |= KVM_PTE_LEAF_ATTR_LO_S2_AF;

	attr |= prot & KVM_PTE_LEAF_ATTR_HI_SW;

	*ptep = attr;



	return 0;
@@ -1025,6 +1027,9 @@ int kvm_pgtable_stage2_relax_perms(struct kvm_pgtable *pgt, u64 addr, 
	u32 level;

	kvm_pte_t set = 0, clr = 0;



	if (prot & KVM_PTE_LEAF_ATTR_HI_SW)

		return -EINVAL;



	if (prot & KVM_PGTABLE_PROT_R)

		set |= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R;