Commit fabf321c authored by Oliver Upton's avatar Oliver Upton
Browse files

KVM: arm64: Handle endianness in read helper for emulated PTW 



Implementing FEAT_HAFDBS means adding another descriptor accessor that
needs to deal with the guest-configured endianness. Prepare by moving
the endianness handling into the read accessor and out of the main body
of the S1/S2 PTWs.

Reviewed-by: default avatarMarc Zyngier <maz@kernel.org>
Tested-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://msgid.link/20251124190158.177318-9-oupton@kernel.org


Signed-off-by: default avatarOliver Upton <oupton@kernel.org>
parent 977d1bf1

arch/arm64/kvm/at.c

+19 −6
Original line number Diff line number Diff line
@@ -362,6 +362,24 @@ static int setup_s1_walk(struct kvm_vcpu *vcpu, struct s1_walk_info *wi, 
	return -EFAULT;

}



static int kvm_read_s1_desc(struct kvm_vcpu *vcpu, u64 pa, u64 *desc,

			    struct s1_walk_info *wi)

{

	u64 val;

	int r;



	r = kvm_read_guest(vcpu->kvm, pa, &val, sizeof(val));

	if (r)

		return r;



	if (wi->be)

		*desc = be64_to_cpu((__force __be64)val);

	else

		*desc = le64_to_cpu((__force __le64)val);



	return 0;

}



static int walk_s1(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,

		   struct s1_walk_result *wr, u64 va)

{
@@ -414,17 +432,12 @@ static int walk_s1(struct kvm_vcpu *vcpu, struct s1_walk_info *wi, 
				return ret;

		}



		ret = kvm_read_guest(vcpu->kvm, ipa, &desc, sizeof(desc));

		ret = kvm_read_s1_desc(vcpu, ipa, &desc, wi);

		if (ret) {

			fail_s1_walk(wr, ESR_ELx_FSC_SEA_TTW(level), false);

			return ret;

		}



		if (wi->be)

			desc = be64_to_cpu((__force __be64)desc);

		else

			desc = le64_to_cpu((__force __le64)desc);



		/* Invalid descriptor */

		if (!(desc & BIT(0)))

			goto transfault;

arch/arm64/kvm/nested.c

+20 −12
Original line number Diff line number Diff line
@@ -197,9 +197,26 @@ static int check_output_size(struct s2_walk_info *wi, phys_addr_t output) 
	return 0;

}



static int read_guest_s2_desc(struct kvm_vcpu *vcpu, phys_addr_t pa, u64 *desc)

static int read_guest_s2_desc(struct kvm_vcpu *vcpu, phys_addr_t pa, u64 *desc,

			      struct s2_walk_info *wi)

{

	return kvm_read_guest(vcpu->kvm, pa, desc, sizeof(*desc));

	u64 val;

	int r;



	r = kvm_read_guest(vcpu->kvm, pa, &val, sizeof(val));

	if (r)

		return r;



	/*

	 * Handle reversedescriptors if endianness differs between the

	 * host and the guest hypervisor.

	 */

	if (wi->be)

		*desc = be64_to_cpu((__force __be64)val);

	else

		*desc = le64_to_cpu((__force __le64)val);



	return 0;

}



/*
@@ -260,19 +277,10 @@ static int walk_nested_s2_pgd(struct kvm_vcpu *vcpu, phys_addr_t ipa, 
			>> (addr_bottom - 3);



		paddr = base_addr | index;

		ret = read_guest_s2_desc(vcpu, paddr, &desc);

		ret = read_guest_s2_desc(vcpu, paddr, &desc, wi);

		if (ret < 0)

			return ret;



		/*

		 * Handle reversedescriptors if endianness differs between the

		 * host and the guest hypervisor.

		 */

		if (wi->be)

			desc = be64_to_cpu((__force __be64)desc);

		else

			desc = le64_to_cpu((__force __le64)desc);



		/* Check for valid descriptor at this point */

		if (!(desc & 1) || ((desc & 3) == 1 && level == 3)) {

			out->esr = compute_fsc(level, ESR_ELx_FSC_FAULT);