linux-kernel - [PATCH RFC 16/22] KVM: x86: hyper-v: Honor HV_STIMER_DIRECT_MODE

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Message-Id: <20210413122630.975617-17-vkuznets@redhat.com>
Date:   Tue, 13 Apr 2021 14:26:24 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Siddharth Chandrasekaran <sidcha@...zon.de>,
        linux-kernel@...r.kernel.org, linux-hyperv@...r.kernel.org
Subject: [PATCH RFC 16/22] KVM: x86: hyper-v: Honor HV_STIMER_DIRECT_MODE_AVAILABLE privilege bit

Synthetic timers can only be configured in 'direct' mode when
HV_STIMER_DIRECT_MODE_AVAILABLE bit was exposed.

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/kvm/hyperv.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 1299847c89ba..0df18187d908 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -646,6 +646,11 @@ static int stimer_set_config(struct kvm_vcpu_hv_stimer *stimer, u64 config,
 				 HV_MSR_SYNTIMER_AVAILABLE))))
 		return 1;
 
+	if (unlikely(!host && new_config.direct_mode &&
+		     !(to_hv_vcpu(vcpu)->cpuid_cache.features_edx &
+		       HV_STIMER_DIRECT_MODE_AVAILABLE)))
+		return 1;
+
 	trace_kvm_hv_stimer_set_config(hv_stimer_to_vcpu(stimer)->vcpu_id,
 				       stimer->index, config, host);
 
-- 
2.30.2