From patchwork Tue Apr 4 15:40:43 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oliver Upton X-Patchwork-Id: 13200509 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22755C6FD1D for ; Tue, 4 Apr 2023 15:42:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235921AbjDDPmB (ORCPT ); Tue, 4 Apr 2023 11:42:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36464 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235940AbjDDPlv (ORCPT ); Tue, 4 Apr 2023 11:41:51 -0400 Received: from out-18.mta0.migadu.com (out-18.mta0.migadu.com [IPv6:2001:41d0:1004:224b::12]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 354B510F6 for ; Tue, 4 Apr 2023 08:41:27 -0700 (PDT) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1680622879; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=mu2eFrZPG8GUOKuHb2kSYzXBqt6mG8kAV7HOxPvOLfI=; b=AHPjRhcZ2uAoGzHTH3EJY/U/h0g94j6fu0lCO8cjWeTXN1NOXeCpkzaB8X0xbFztgXEn6d nBXLHi2BfcKoAi2B5rB8OeV8XFmhO8LOTN3hEPmrXahbUQrsjwI3iyeOiFZP66454nmin+ HcQ34ETK2i2GnSRsqytLztq720vmLfI= From: Oliver Upton To: kvmarm@lists.linux.dev Cc: kvm@vger.kernel.org, Paolo Bonzini , Marc Zyngier , James Morse , Suzuki K Poulose , Zenghui Yu , Sean Christopherson , Salil Mehta , Oliver Upton Subject: [PATCH v3 06/13] KVM: arm64: Refactor hvc filtering to support different actions Date: Tue, 4 Apr 2023 15:40:43 +0000 Message-Id: <20230404154050.2270077-7-oliver.upton@linux.dev> In-Reply-To: <20230404154050.2270077-1-oliver.upton@linux.dev> References: <20230404154050.2270077-1-oliver.upton@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org KVM presently allows userspace to filter guest hypercalls with bitmaps expressed via pseudo-firmware registers. These bitmaps have a narrow scope and, of course, can only allow/deny a particular call. A subsequent change to KVM will introduce a generalized UAPI for filtering hypercalls, allowing functions to be forwarded to userspace. Refactor the existing hypercall filtering logic to make room for more than two actions. While at it, generalize the function names around SMCCC as it is the basis for the upcoming UAPI. No functional change intended. Reviewed-by: Suzuki K Poulose Signed-off-by: Oliver Upton --- arch/arm64/include/uapi/asm/kvm.h | 9 +++++++++ arch/arm64/kvm/hypercalls.c | 26 ++++++++++++++++++++++---- 2 files changed, 31 insertions(+), 4 deletions(-) diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h index f8129c624b07..f9672ef1159a 100644 --- a/arch/arm64/include/uapi/asm/kvm.h +++ b/arch/arm64/include/uapi/asm/kvm.h @@ -469,6 +469,15 @@ enum { /* run->fail_entry.hardware_entry_failure_reason codes. */ #define KVM_EXIT_FAIL_ENTRY_CPU_UNSUPPORTED (1ULL << 0) +enum kvm_smccc_filter_action { + KVM_SMCCC_FILTER_HANDLE = 0, + KVM_SMCCC_FILTER_DENY, + +#ifdef __KERNEL__ + NR_SMCCC_FILTER_ACTIONS +#endif +}; + #endif #endif /* __ARM_KVM_H__ */ diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c index 5ead6c6afff0..0be974e2f1fc 100644 --- a/arch/arm64/kvm/hypercalls.c +++ b/arch/arm64/kvm/hypercalls.c @@ -65,7 +65,7 @@ static void kvm_ptp_get_time(struct kvm_vcpu *vcpu, u64 *val) val[3] = lower_32_bits(cycles); } -static bool kvm_hvc_call_default_allowed(u32 func_id) +static bool kvm_smccc_default_allowed(u32 func_id) { switch (func_id) { /* @@ -93,7 +93,7 @@ static bool kvm_hvc_call_default_allowed(u32 func_id) } } -static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id) +static bool kvm_smccc_test_fw_bmap(struct kvm_vcpu *vcpu, u32 func_id) { struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat; @@ -117,20 +117,38 @@ static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id) return test_bit(KVM_REG_ARM_VENDOR_HYP_BIT_PTP, &smccc_feat->vendor_hyp_bmap); default: - return kvm_hvc_call_default_allowed(func_id); + return false; } } +static u8 kvm_smccc_get_action(struct kvm_vcpu *vcpu, u32 func_id) +{ + if (kvm_smccc_test_fw_bmap(vcpu, func_id) || + kvm_smccc_default_allowed(func_id)) + return KVM_SMCCC_FILTER_HANDLE; + + return KVM_SMCCC_FILTER_DENY; +} + int kvm_smccc_call_handler(struct kvm_vcpu *vcpu) { struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat; u32 func_id = smccc_get_function(vcpu); u64 val[4] = {SMCCC_RET_NOT_SUPPORTED}; u32 feature; + u8 action; gpa_t gpa; - if (!kvm_hvc_call_allowed(vcpu, func_id)) + action = kvm_smccc_get_action(vcpu, func_id); + switch (action) { + case KVM_SMCCC_FILTER_HANDLE: + break; + case KVM_SMCCC_FILTER_DENY: + goto out; + default: + WARN_RATELIMIT(1, "Unhandled SMCCC filter action: %d\n", action); goto out; + } switch (func_id) { case ARM_SMCCC_VERSION_FUNC_ID: