[RFC PATCH 31/73] KVM: x86/PVM: Implement instruction emulation for #UD and #GP

Lai Jiangshan
2024-02-26T14:36:19Z

The privilege instruction in supervisor mode will trigger a #GP and
induce VM exit. Therefore, PVM reuses the existing x86 emulator in PVM
to support privilege instruction emulation in supervisor mode.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
---
arch/x86/kvm/pvm/pvm.c | 38 ++++++++++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)

diff --git a/arch/x86/kvm/pvm/pvm.c b/arch/x86/kvm/pvm/pvm.c
index 6f91dffb6c50..4ec8c2c514ca 100644
--- a/arch/x86/kvm/pvm/pvm.c
+++ b/arch/x86/kvm/pvm/pvm.c
@@ -402,6 +402,40 @@ static void pvm_sched_in(struct kvm_vcpu *vcpu, int cpu)
{
}

+static void pvm_patch_hypercall(struct kvm_vcpu *vcpu, unsigned char *hypercall)
+{
+ /* KVM_X86_QUIRK_FIX_HYPERCALL_INSN should not be enabled for pvm guest */
+
+ /* ud2; int3; */
+ hypercall[0] = 0x0F;
+ hypercall[1] = 0x0B;
+ hypercall[2] = 0xCC;
+}
+
+static int pvm_check_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type,
+ void *insn, int insn_len)
+{
+ return X86EMUL_CONTINUE;
+}
+
+static int skip_emulated_instruction(struct kvm_vcpu *vcpu)
+{
+ return kvm_emulate_instruction(vcpu, EMULTYPE_SKIP);
+}
+
+static int pvm_check_intercept(struct kvm_vcpu *vcpu,
+ struct x86_instruction_info *info,
+ enum x86_intercept_stage stage,
+ struct x86_exception *exception)
+{
+ /*
+ * HF_GUEST_MASK is not used even nested pvm is supported. L0 pvm
+ * might even be unaware the L1 pvm.
+ */
+ WARN_ON_ONCE(1);
+ return X86EMUL_CONTINUE;
+}
+
static void pvm_set_msr_linear_address_range(struct vcpu_pvm *pvm,
u64 pml4_i_s, u64 pml4_i_e,
u64 pml5_i_s, u64 pml5_i_e)
@@ -1682,8 +1716,10 @@ static struct kvm_x86_ops pvm_x86_ops __initdata = {
.vcpu_pre_run = pvm_vcpu_pre_run,
.vcpu_run = pvm_vcpu_run,
.handle_exit = pvm_handle_exit,
+ .skip_emulated_instruction = skip_emulated_instruction,
.set_interrupt_shadow = pvm_set_interrupt_shadow,
.get_interrupt_shadow = pvm_get_interrupt_shadow,
+ .patch_hypercall = pvm_patch_hypercall,
.inject_irq = pvm_inject_irq,
.inject_nmi = pvm_inject_nmi,
.inject_exception = pvm_inject_exception,
@@ -1699,6 +1735,7 @@ static struct kvm_x86_ops pvm_x86_ops __initdata = {

.vcpu_after_set_cpuid = pvm_vcpu_after_set_cpuid,

+ .check_intercept = pvm_check_intercept,
.handle_exit_irqoff = pvm_handle_exit_irqoff,

.request_immediate_exit = __kvm_request_immediate_exit,
@@ -1721,6 +1758,7 @@ static struct kvm_x86_ops pvm_x86_ops __initdata = {
.complete_emulated_msr = kvm_complete_insn_gp,
.vcpu_deliver_sipi_vector = kvm_vcpu_deliver_sipi_vector,

+ .check_emulate_instruction = pvm_check_emulate_instruction,
.disallowed_va = pvm_disallowed_va,
.vcpu_gpc_refresh = pvm_vcpu_gpc_refresh,
};
--
2.19.1.6.gb485710b