Commit 52b28657 authored by Quentin Perret's avatar Quentin Perret Committed by Marc Zyngier
Browse files

KVM: arm64: pkvm: Unshare guest structs during teardown 



Make use of the newly introduced unshare hypercall during guest teardown
to unmap guest-related data structures from the hyp stage-1.

Signed-off-by: default avatarQuentin Perret <qperret@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211215161232.1480836-15-qperret@google.com
parent b8cc6eb5

arch/arm64/include/asm/kvm_host.h

+2 −0
Original line number Diff line number Diff line
@@ -321,6 +321,7 @@ struct kvm_vcpu_arch { 
	struct kvm_guest_debug_arch external_debug_state;



	struct user_fpsimd_state *host_fpsimd_state;	/* hyp VA */

	struct task_struct *parent_task;



	struct {

		/* {Break,watch}point registers */
@@ -737,6 +738,7 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu); 
void kvm_arch_vcpu_ctxflush_fp(struct kvm_vcpu *vcpu);

void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu);

void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu);

void kvm_vcpu_unshare_task_fp(struct kvm_vcpu *vcpu);



static inline bool kvm_pmu_counter_deferred(struct perf_event_attr *attr)

{

arch/arm64/include/asm/kvm_mmu.h

+1 −0
Original line number Diff line number Diff line
@@ -151,6 +151,7 @@ static __always_inline unsigned long __kern_hyp_va(unsigned long v) 
#include <asm/stage2_pgtable.h>



int kvm_share_hyp(void *from, void *to);

void kvm_unshare_hyp(void *from, void *to);

int create_hyp_mappings(void *from, void *to, enum kvm_pgtable_prot prot);

int create_hyp_io_mappings(phys_addr_t phys_addr, size_t size,

			   void __iomem **kaddr,

arch/arm64/kvm/arm.c

+2 −0
Original line number Diff line number Diff line
@@ -188,6 +188,8 @@ void kvm_arch_destroy_vm(struct kvm *kvm) 
		}

	}

	atomic_set(&kvm->online_vcpus, 0);



	kvm_unshare_hyp(kvm, kvm + 1);

}



int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)

arch/arm64/kvm/fpsimd.c

+31 −3
Original line number Diff line number Diff line
@@ -14,6 +14,19 @@ 
#include <asm/kvm_mmu.h>

#include <asm/sysreg.h>



void kvm_vcpu_unshare_task_fp(struct kvm_vcpu *vcpu)

{

	struct task_struct *p = vcpu->arch.parent_task;

	struct user_fpsimd_state *fpsimd;



	if (!is_protected_kvm_enabled() || !p)

		return;



	fpsimd = &p->thread.uw.fpsimd_state;

	kvm_unshare_hyp(fpsimd, fpsimd + 1);

	put_task_struct(p);

}



/*

 * Called on entry to KVM_RUN unless this vcpu previously ran at least

 * once and the most recent prior KVM_RUN for this vcpu was called from
@@ -29,12 +42,27 @@ int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu) 


	struct user_fpsimd_state *fpsimd = &current->thread.uw.fpsimd_state;



	kvm_vcpu_unshare_task_fp(vcpu);



	/* Make sure the host task fpsimd state is visible to hyp: */

	ret = kvm_share_hyp(fpsimd, fpsimd + 1);

	if (!ret)

	if (ret)

		return ret;



	vcpu->arch.host_fpsimd_state = kern_hyp_va(fpsimd);



	return ret;

	/*

	 * We need to keep current's task_struct pinned until its data has been

	 * unshared with the hypervisor to make sure it is not re-used by the

	 * kernel and donated to someone else while already shared -- see

	 * kvm_vcpu_unshare_task_fp() for the matching put_task_struct().

	 */

	if (is_protected_kvm_enabled()) {

		get_task_struct(current);

		vcpu->arch.parent_task = current;

	}



	return 0;

}



/*

arch/arm64/kvm/mmu.c

+42 −0
Original line number Diff line number Diff line
@@ -341,6 +341,32 @@ static int share_pfn_hyp(u64 pfn) 
	return ret;

}



static int unshare_pfn_hyp(u64 pfn)

{

	struct rb_node **node, *parent;

	struct hyp_shared_pfn *this;

	int ret = 0;



	mutex_lock(&hyp_shared_pfns_lock);

	this = find_shared_pfn(pfn, &node, &parent);

	if (WARN_ON(!this)) {

		ret = -ENOENT;

		goto unlock;

	}



	this->count--;

	if (this->count)

		goto unlock;



	rb_erase(&this->node, &hyp_shared_pfns);

	kfree(this);

	ret = kvm_call_hyp_nvhe(__pkvm_host_unshare_hyp, pfn, 1);

unlock:

	mutex_unlock(&hyp_shared_pfns_lock);



	return ret;

}



int kvm_share_hyp(void *from, void *to)

{

	phys_addr_t start, end, cur;
@@ -373,6 +399,22 @@ int kvm_share_hyp(void *from, void *to) 
	return 0;

}



void kvm_unshare_hyp(void *from, void *to)

{

	phys_addr_t start, end, cur;

	u64 pfn;



	if (is_kernel_in_hyp_mode() || kvm_host_owns_hyp_mappings() || !from)

		return;



	start = ALIGN_DOWN(__pa(from), PAGE_SIZE);

	end = PAGE_ALIGN(__pa(to));

	for (cur = start; cur < end; cur += PAGE_SIZE) {

		pfn = __phys_to_pfn(cur);

		WARN_ON(unshare_pfn_hyp(pfn));

	}

}



/**

 * create_hyp_mappings - duplicate a kernel virtual address range in Hyp mode

 * @from:	The virtual kernel start address of the range