[PATCH 12/22] KVM: x86: Fold retry_instruction() into x86_emulate_instruction()

From: Sean Christopherson
Date: Fri Aug 09 2024 - 15:07:20 EST


Now that retry_instruction() is reasonably tiny, fold it into its sole
caller, x86_emulate_instruction(). In addition to getting rid of the
absurdly confusing retry_instruction() name, handling the retry in
x86_emulate_instruction() pairs it back up with the code that resets
last_retry_{eip,address}.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/x86.c | 30 +++++++++---------------------
1 file changed, 9 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7e90c3b888c2..771e67381fce 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8926,26 +8926,6 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
return !(emulation_type & EMULTYPE_WRITE_PF_TO_SP);
}

-static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
- gpa_t cr2_or_gpa, int emulation_type)
-{
- struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
-
- /*
- * If the emulation is caused by #PF and it is non-page_table
- * writing instruction, it means the VM-EXIT is caused by shadow
- * page protected, we can zap the shadow page and retry this
- * instruction directly.
- */
- if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF))
- return false;
-
- if (x86_page_table_writing_insn(ctxt))
- return false;
-
- return kvm_mmu_unprotect_gfn_and_retry(vcpu, cr2_or_gpa);
-}
-
static int complete_emulated_mmio(struct kvm_vcpu *vcpu);
static int complete_emulated_pio(struct kvm_vcpu *vcpu);

@@ -9225,7 +9205,15 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
return 1;
}

- if (retry_instruction(ctxt, cr2_or_gpa, emulation_type))
+ /*
+ * If emulation was caused by a write-protection #PF on a non-page_table
+ * writing instruction, try to unprotect the gfn, i.e. zap shadow pages,
+ * and retry the instruction, as the vCPU is likely no longer using the
+ * gfn as a page table.
+ */
+ if ((emulation_type & EMULTYPE_ALLOW_RETRY_PF) &&
+ !x86_page_table_writing_insn(ctxt) &&
+ kvm_mmu_unprotect_gfn_and_retry(vcpu, cr2_or_gpa))
return 1;

/* this is needed for vmware backdoor interface to work since it
--
2.46.0.76.ge559c4bf1a-goog