[PATCH v19 097/130] KVM: x86: Split core of hypercall emulation to helper function

isaku.yamahata
2024-02-26T08:28:55Z

From: Sean Christopherson <sean.j.christopherson@intel.com>

By necessity, TDX will use a different register ABI for hypercalls.
Break out the core functionality so that it may be reused for TDX.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
arch/x86/include/asm/kvm_host.h | 4 +++
arch/x86/kvm/x86.c | 56 ++++++++++++++++++++++-----------
2 files changed, 42 insertions(+), 18 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index e0ffef1d377d..bb8be091f996 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -2177,6 +2177,10 @@ static inline void kvm_clear_apicv_inhibit(struct kvm *kvm,
kvm_set_or_clear_apicv_inhibit(kvm, reason, false);
}

+unsigned long __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr,
+ unsigned long a0, unsigned long a1,
+ unsigned long a2, unsigned long a3,
+ int op_64_bit, int cpl);
int kvm_emulate_hypercall(struct kvm_vcpu *vcpu);

int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fb7597c22f31..03950368d8db 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10073,26 +10073,15 @@ static int complete_hypercall_exit(struct kvm_vcpu *vcpu)
return kvm_skip_emulated_instruction(vcpu);
}

-int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
+unsigned long __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr,
+ unsigned long a0, unsigned long a1,
+ unsigned long a2, unsigned long a3,
+ int op_64_bit, int cpl)
{
- unsigned long nr, a0, a1, a2, a3, ret;
- int op_64_bit;
-
- if (kvm_xen_hypercall_enabled(vcpu->kvm))
- return kvm_xen_hypercall(vcpu);
-
- if (kvm_hv_hypercall_enabled(vcpu))
- return kvm_hv_hypercall(vcpu);
-
- nr = kvm_rax_read(vcpu);
- a0 = kvm_rbx_read(vcpu);
- a1 = kvm_rcx_read(vcpu);
- a2 = kvm_rdx_read(vcpu);
- a3 = kvm_rsi_read(vcpu);
+ unsigned long ret;

trace_kvm_hypercall(nr, a0, a1, a2, a3);

- op_64_bit = is_64_bit_hypercall(vcpu);
if (!op_64_bit) {
nr &= 0xFFFFFFFF;
a0 &= 0xFFFFFFFF;
@@ -10101,7 +10090,7 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
a3 &= 0xFFFFFFFF;
}

- if (static_call(kvm_x86_get_cpl)(vcpu) != 0) {
+ if (cpl) {
ret = -KVM_EPERM;
goto out;
}
@@ -10162,18 +10151,49 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)

WARN_ON_ONCE(vcpu->run->hypercall.flags & KVM_EXIT_HYPERCALL_MBZ);
vcpu->arch.complete_userspace_io = complete_hypercall_exit;
+ /* stat is incremented on completion. */
return 0;
}
default:
ret = -KVM_ENOSYS;
break;
}
+
out:
+ ++vcpu->stat.hypercalls;
+ return ret;
+}
+EXPORT_SYMBOL_GPL(__kvm_emulate_hypercall);
+
+int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
+{
+ unsigned long nr, a0, a1, a2, a3, ret;
+ int op_64_bit;
+ int cpl;
+
+ if (kvm_xen_hypercall_enabled(vcpu->kvm))
+ return kvm_xen_hypercall(vcpu);
+
+ if (kvm_hv_hypercall_enabled(vcpu))
+ return kvm_hv_hypercall(vcpu);
+
+ nr = kvm_rax_read(vcpu);
+ a0 = kvm_rbx_read(vcpu);
+ a1 = kvm_rcx_read(vcpu);
+ a2 = kvm_rdx_read(vcpu);
+ a3 = kvm_rsi_read(vcpu);
+ op_64_bit = is_64_bit_hypercall(vcpu);
+ cpl = static_call(kvm_x86_get_cpl)(vcpu);
+
+ ret = __kvm_emulate_hypercall(vcpu, nr, a0, a1, a2, a3, op_64_bit, cpl);
+ if (nr == KVM_HC_MAP_GPA_RANGE && !ret)
+ /* MAP_GPA tosses the request to the user space. */
+ return 0;
+
if (!op_64_bit)
ret = (u32)ret;
kvm_rax_write(vcpu, ret);

- ++vcpu->stat.hypercalls;
return kvm_skip_emulated_instruction(vcpu);
}
EXPORT_SYMBOL_GPL(kvm_emulate_hypercall);
--
2.25.1