linux-kernel - [PATCH 1/5] KVM: nSVM: Sync next_rip field from vmcb12 to vmcb02

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Date:   Thu, 10 Mar 2022 22:38:37 +0100
From:   "Maciej S. Szmigiero" <mail@...iej.szmigiero.name>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Brijesh Singh <brijesh.singh@....com>,
        Jon Grimm <Jon.Grimm@....com>,
        David Kaplan <David.Kaplan@....com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Liam Merwick <liam.merwick@...cle.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/5] KVM: nSVM: Sync next_rip field from vmcb12 to vmcb02

From: "Maciej S. Szmigiero" <maciej.szmigiero@...cle.com>

The next_rip field of a VMCB is *not* an output-only field for a VMRUN.
This field value (instead of the saved guest RIP) in used by the CPU for
the return address pushed on stack when injecting a software interrupt or
INT3 or INTO exception.

Make sure this field gets synced from vmcb12 to vmcb02 when entering L2 or
loading a nested state.

Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@...cle.com>
---
 arch/x86/kvm/svm/nested.c | 4 ++++
 arch/x86/kvm/svm/svm.h    | 1 +
 2 files changed, 5 insertions(+)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index d736ec6514ca..9656f0d6815c 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -366,6 +366,7 @@ void __nested_copy_vmcb_control_to_cache(struct kvm_vcpu *vcpu,
 	to->nested_ctl          = from->nested_ctl;
 	to->event_inj           = from->event_inj;
 	to->event_inj_err       = from->event_inj_err;
+	to->next_rip            = from->next_rip;
 	to->nested_cr3          = from->nested_cr3;
 	to->virt_ext            = from->virt_ext;
 	to->pause_filter_count  = from->pause_filter_count;
@@ -638,6 +639,8 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm)
 	svm->vmcb->control.int_state           = svm->nested.ctl.int_state;
 	svm->vmcb->control.event_inj           = svm->nested.ctl.event_inj;
 	svm->vmcb->control.event_inj_err       = svm->nested.ctl.event_inj_err;
+	/* The return address pushed on stack by the CPU for some injected events */
+	svm->vmcb->control.next_rip            = svm->nested.ctl.next_rip;
 
 	if (!nested_vmcb_needs_vls_intercept(svm))
 		svm->vmcb->control.virt_ext |= VIRTUAL_VMLOAD_VMSAVE_ENABLE_MASK;
@@ -1348,6 +1351,7 @@ static void nested_copy_vmcb_cache_to_control(struct vmcb_control_area *dst,
 	dst->nested_ctl           = from->nested_ctl;
 	dst->event_inj            = from->event_inj;
 	dst->event_inj_err        = from->event_inj_err;
+	dst->next_rip             = from->next_rip;
 	dst->nested_cr3           = from->nested_cr3;
 	dst->virt_ext              = from->virt_ext;
 	dst->pause_filter_count   = from->pause_filter_count;
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 93502d2a52ce..f757400fc933 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -138,6 +138,7 @@ struct vmcb_ctrl_area_cached {
 	u64 nested_ctl;
 	u32 event_inj;
 	u32 event_inj_err;
+	u64 next_rip;
 	u64 nested_cr3;
 	u64 virt_ext;
 	u32 clean;