Commit e8d16497 authored by Shaoqin Huang's avatar Shaoqin Huang Committed by Marc Zyngier
Browse files

KVM: arm64: Use kvm_has_feat() to check if FEAT_SSBS is advertised to the guest 



Currently KVM use cpus_have_final_cap() to check if FEAT_SSBS is
advertised to the guest. But if FEAT_SSBS is writable and isn't
advertised to the guest, this is wrong.

Update it to use kvm_has_feat() to check if FEAT_SSBS is advertised
to the guest, thus the KVM can do the right thing if FEAT_SSBS isn't
advertised to the guest.

Signed-off-by: default avatarShaoqin Huang <shahuang@redhat.com>
Link: https://lore.kernel.org/r/20240723072004.1470688-3-shahuang@redhat.com


Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent ffe68b2d

arch/arm64/kvm/hypercalls.c

+6 −6
Original line number Diff line number Diff line
@@ -317,7 +317,7 @@ int kvm_smccc_call_handler(struct kvm_vcpu *vcpu) 
				 * to the guest, and hide SSBS so that the

				 * guest stays protected.

				 */

				if (cpus_have_final_cap(ARM64_SSBS))

				if (kvm_has_feat(vcpu->kvm, ID_AA64PFR1_EL1, SSBS, IMP))

					break;

				fallthrough;

			case SPECTRE_UNAFFECTED:
@@ -428,7 +428,7 @@ int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices) 
 * Convert the workaround level into an easy-to-compare number, where higher

 * values mean better protection.

 */

static int get_kernel_wa_level(u64 regid)

static int get_kernel_wa_level(struct kvm_vcpu *vcpu, u64 regid)

{

	switch (regid) {

	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
@@ -449,7 +449,7 @@ static int get_kernel_wa_level(u64 regid) 
			 * don't have any FW mitigation if SSBS is there at

			 * all times.

			 */

			if (cpus_have_final_cap(ARM64_SSBS))

			if (kvm_has_feat(vcpu->kvm, ID_AA64PFR1_EL1, SSBS, IMP))

				return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;

			fallthrough;

		case SPECTRE_UNAFFECTED:
@@ -486,7 +486,7 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) 
	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:

	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:

	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:

		val = get_kernel_wa_level(reg->id) & KVM_REG_FEATURE_LEVEL_MASK;

		val = get_kernel_wa_level(vcpu, reg->id) & KVM_REG_FEATURE_LEVEL_MASK;

		break;

	case KVM_REG_ARM_STD_BMAP:

		val = READ_ONCE(smccc_feat->std_bmap);
@@ -588,7 +588,7 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) 
		if (val & ~KVM_REG_FEATURE_LEVEL_MASK)

			return -EINVAL;



		if (get_kernel_wa_level(reg->id) < val)

		if (get_kernel_wa_level(vcpu, reg->id) < val)

			return -EINVAL;



		return 0;
@@ -624,7 +624,7 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) 
		 * We can deal with NOT_AVAIL on NOT_REQUIRED, but not the

		 * other way around.

		 */

		if (get_kernel_wa_level(reg->id) < wa_level)

		if (get_kernel_wa_level(vcpu, reg->id) < wa_level)

			return -EINVAL;



		return 0;