KVM: x86: Plumb the emulator's starting RIP into nested intercept checks

When checking for intercept when emulating an instruction on behalf of L2,
pass the emulator's view of the RIP of the instruction being emulated to
vendor code.  Unlike SVM, which communicates the next RIP on VM-Exit,
VMX communicates the length of the instruction that generated the VM-Exit,
i.e. requires the current and next RIPs.

Note, unless userspace modifies RIP during a userspace exit that requires
completion, kvm_rip_read() will contain the same information.  Pass the
emulator's view largely out of a paranoia, and because there is no
meaningful cost in doing so.

Link: https://lore.kernel.org/r/20250201015518.689704-8-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index ca613796b5afe9eb30f484af41f687e52a1a2fed..1349e278cd2a13820a5dd021defe4f508146fe5e 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -480,6 +480,7 @@ static int emulator_check_intercept(struct x86_emulate_ctxt *ctxt,
                .src_type   = ctxt->src.type,
                .dst_type   = ctxt->dst.type,
                .ad_bytes   = ctxt->ad_bytes,
+               .rip        = ctxt->eip,
                .next_rip   = ctxt->_eip,
        };
 

diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h
index 49ab8b060137a715886f064c548ee353b67ca8d2..35029b12667f2b7798ee9b83c4d0e1c868c16398 100644 (file)
--- a/arch/x86/kvm/kvm_emulate.h
+++ b/arch/x86/kvm/kvm_emulate.h
@@ -47,6 +47,7 @@ struct x86_instruction_info {
        u8  src_type;           /* type of source operand               */
        u8  dst_type;           /* type of destination operand          */
        u8  ad_bytes;           /* size of src/dst address              */
+       u64 rip;                /* rip of the instruction               */
        u64 next_rip;           /* rip following the instruction        */
 };