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From:   Vitaly Kuznetsov <vkuznets@redhat.com>
To:     kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>
Cc:     Sean Christopherson <seanjc@google.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Siddharth Chandrasekaran <sidcha@amazon.de>,
        linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org
Subject: [PATCH RFC 21/22] KVM: x86: hyper-v: Honor HV_X64_CLUSTER_IPI_RECOMMENDED bit
Date:   Tue, 13 Apr 2021 14:26:29 +0200
Message-Id: <20210413122630.975617-22-vkuznets@redhat.com>
In-Reply-To: <20210413122630.975617-1-vkuznets@redhat.com>
References: <20210413122630.975617-1-vkuznets@redhat.com>
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Hyper-V partition must possess 'HV_X64_CLUSTER_IPI_RECOMMENDED'
privilege ('recommended' is rather a misnomer) to issue
HVCALL_SEND_IPI hypercalls. 'HVCALL_SEND_IPI_EX' version of the
hypercall also requires HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 arch/x86/kvm/hyperv.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 3e8a34c08aef..37b8ff30fc1d 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -2211,6 +2211,12 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 		ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, true);
 		break;
 	case HVCALL_SEND_IPI:
+		if (unlikely(!(hv_vcpu->cpuid_cache.enlightenments_eax &
+			       HV_X64_CLUSTER_IPI_RECOMMENDED))) {
+			ret = HV_STATUS_ACCESS_DENIED;
+			break;
+		}
+
 		if (unlikely(rep)) {
 			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
 			break;
@@ -2218,6 +2224,14 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 		ret = kvm_hv_send_ipi(vcpu, ingpa, outgpa, false, fast);
 		break;
 	case HVCALL_SEND_IPI_EX:
+		if (unlikely(!(hv_vcpu->cpuid_cache.enlightenments_eax &
+			       HV_X64_CLUSTER_IPI_RECOMMENDED) ||
+			     !(hv_vcpu->cpuid_cache.enlightenments_eax &
+			       HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))) {
+			ret = HV_STATUS_ACCESS_DENIED;
+			break;
+		}
+
 		if (unlikely(fast || rep)) {
 			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
 			break;
-- 
2.30.2