From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 05/10] KVM: nVMX: Avoid retpoline when writing DR7 during nested transitions
Date: Fri, 1 May 2020 21:32:29 -0700 [thread overview]
Message-ID: <20200502043234.12481-6-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20200502043234.12481-1-sean.j.christopherson@intel.com>
Add a helper, nested_vmx_set_dr7(), to handle updating DR7 during nested
transitions to avoid bouncing through kvm_update_dr7() and its
potentially retpolined kvm_x86_ops.set_dr7() call. The duplicated code
to adjust the architectural DR7 is minor, and losing the WARN_ON() when
refreshing DR7 from vmcs01 is really no loss at all.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/vmx/nested.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 1f2f41e821f9..3b4f1408b4e1 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2116,6 +2116,12 @@ static void vmx_start_preemption_timer(struct kvm_vcpu *vcpu)
ns_to_ktime(preemption_timeout), HRTIMER_MODE_REL);
}
+static void nested_vmx_set_dr7(struct kvm_vcpu *vcpu, unsigned long val)
+{
+ vcpu->arch.dr7 = (val & DR7_VOLATILE) | DR7_FIXED_1;
+ vmcs_writel(GUEST_DR7, __kvm_update_dr7(vcpu));
+}
+
static u64 nested_vmx_calc_efer(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
{
if (vmx->nested.nested_run_pending &&
@@ -2487,10 +2493,10 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
if (vmx->nested.nested_run_pending &&
(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS)) {
- kvm_set_dr(vcpu, 7, vmcs12->guest_dr7);
+ nested_vmx_set_dr7(vcpu, vmcs12->guest_dr7);
vmcs_write64(GUEST_IA32_DEBUGCTL, vmcs12->guest_ia32_debugctl);
} else {
- kvm_set_dr(vcpu, 7, vcpu->arch.dr7);
+ nested_vmx_set_dr7(vcpu, vcpu->arch.dr7);
vmcs_write64(GUEST_IA32_DEBUGCTL, vmx->nested.vmcs01_debugctl);
}
if (kvm_mpx_supported() && (!vmx->nested.nested_run_pending ||
@@ -4176,7 +4182,7 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
};
vmx_set_segment(vcpu, &seg, VCPU_SREG_TR);
- kvm_set_dr(vcpu, 7, 0x400);
+ nested_vmx_set_dr7(vcpu, 0x400);
vmcs_write64(GUEST_IA32_DEBUGCTL, 0);
if (cpu_has_vmx_msr_bitmap())
@@ -4228,9 +4234,9 @@ static void nested_vmx_restore_host_state(struct kvm_vcpu *vcpu)
* nested VMENTER (not worth adding a variable in nested_vmx).
*/
if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)
- kvm_set_dr(vcpu, 7, DR7_FIXED_1);
+ nested_vmx_set_dr7(vcpu, DR7_FIXED_1);
else
- WARN_ON(kvm_set_dr(vcpu, 7, vmcs_readl(GUEST_DR7)));
+ nested_vmx_set_dr7(vcpu, vmcs_readl(GUEST_DR7));
}
/*
--
2.26.0
next prev parent reply other threads:[~2020-05-02 4:33 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-02 4:32 [PATCH 00/10] KVM: x86: Misc anti-retpoline optimizations Sean Christopherson
2020-05-02 4:32 ` [PATCH 01/10] KVM: x86: Save L1 TSC offset in 'struct kvm_vcpu_arch' Sean Christopherson
2020-05-02 4:32 ` [PATCH 02/10] KVM: nVMX: Unconditionally validate CR3 during nested transitions Sean Christopherson
2020-05-02 4:32 ` [PATCH 03/10] KVM: x86: Make kvm_x86_ops' {g,s}et_dr6() hooks optional Sean Christopherson
2020-05-04 13:19 ` Paolo Bonzini
2020-05-02 4:32 ` [PATCH 04/10] KVM: x86: Split guts of kvm_update_dr7() to separate helper Sean Christopherson
2020-05-02 4:32 ` Sean Christopherson [this message]
2020-05-02 4:32 ` [PATCH 06/10] KVM: VMX: Add proper cache tracking for CR4 Sean Christopherson
2020-05-02 4:32 ` [PATCH 07/10] KVM: VMX: Add proper cache tracking for CR0 Sean Christopherson
2020-05-02 4:32 ` [PATCH 08/10] KVM: VMX: Add anti-retpoline accessors for RIP and RSP Sean Christopherson
2020-05-02 4:32 ` [PATCH 09/10] KVM: VMX: Move nested EPT out of kvm_x86_ops.get_tdp_level() hook Sean Christopherson
2020-05-02 4:32 ` [PATCH 10/10] KVM: x86/mmu: Capture TDP level when updating CPUID Sean Christopherson
2020-05-04 13:25 ` [PATCH 00/10] KVM: x86: Misc anti-retpoline optimizations Paolo Bonzini
2020-05-04 15:09 ` Sean Christopherson
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