From c8e612bfedff67da0dd4abdf4de9ce7671b89f71 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 31 Jan 2025 17:55:09 -0800 Subject: [PATCH] KVM: nSVM: Pass next RIP, not current RIP, for nested VM-Exit on emulation Set "next_rip" in the emulation interception info passed to vendor code using the emulator context's "_eip", not "eip". "eip" holds RIP from the start of emulation, i.e. the RIP of the instruction that's being emulated, whereas _eip tracks the context's current position in decoding the code stream, which at the time of the intercept checks is effectively the RIP of the next instruction. Passing the current RIP as next_rip causes SVM to stuff the wrong value value into vmcb12->control.next_rip if a nested VM-Exit is generated, i.e. if L1 wants to intercept the instruction, and could result in L1 putting L2 into an infinite loop due to restarting L2 with the same RIP over and over. Fixes: 8a76d7f25f8f ("KVM: x86: Add x86 callback for intercept check") Link: https://lore.kernel.org/r/20250201015518.689704-3-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/emulate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 60986f67c35a8..0915b5e8aa717 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -478,7 +478,7 @@ static int emulator_check_intercept(struct x86_emulate_ctxt *ctxt, .src_bytes = ctxt->src.bytes, .dst_bytes = ctxt->dst.bytes, .ad_bytes = ctxt->ad_bytes, - .next_rip = ctxt->eip, + .next_rip = ctxt->_eip, }; return ctxt->ops->intercept(ctxt, &info, stage); -- 2.47.2