linux-kernel - [PATCH 2/2] KVM: x86: Do not use kvm_rip_read() unconditionally for KVM

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Message-ID: <20250415104821.247234-3-adrian.hunter@intel.com>
Date: Tue, 15 Apr 2025 13:48:21 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: pbonzini@...hat.com,
	seanjc@...gle.com
Cc: kvm@...r.kernel.org,
	rick.p.edgecombe@...el.com,
	kirill.shutemov@...ux.intel.com,
	kai.huang@...el.com,
	reinette.chatre@...el.com,
	xiaoyao.li@...el.com,
	tony.lindgren@...ux.intel.com,
	binbin.wu@...ux.intel.com,
	isaku.yamahata@...el.com,
	linux-kernel@...r.kernel.org,
	yan.y.zhao@...el.com,
	chao.gao@...el.com
Subject: [PATCH 2/2] KVM: x86: Do not use kvm_rip_read() unconditionally for KVM_PROFILING

Not all VMs allow access to RIP.  Check guest_state_protected before
calling kvm_rip_read().

This avoids, for example, hitting WARN_ON_ONCE in vt_cache_reg() for
TDX VMs.

Fixes: 81bf912b2c15 ("KVM: TDX: Implement TDX vcpu enter/exit path")
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 arch/x86/kvm/x86.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 844e81ee1d96..8758f8cba488 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11130,7 +11130,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 	/*
 	 * Profile KVM exit RIPs:
 	 */
-	if (unlikely(prof_on == KVM_PROFILING)) {
+	if (unlikely(prof_on == KVM_PROFILING &&
+		     !vcpu->arch.guest_state_protected)) {
 		unsigned long rip = kvm_rip_read(vcpu);
 		profile_hit(KVM_PROFILING, (void *)rip);
 	}
-- 
2.43.0