[PATCH v4 2/6] KVM: x86: Add a helper to check for user interception of KVM hypercalls

Sean Christopherson
2024-11-28T00:43:51Z

From: Binbin Wu <binbin.wu@linux.intel.com>

Add and use user_exit_on_hypercall() to check if userspace wants to handle
a KVM hypercall instead of open-coding the logic everywhere.

No functional change intended.

Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
[sean: squash into one patch, keep explicit KVM_HC_MAP_GPA_RANGE check]
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/svm/sev.c | 4 ++--
arch/x86/kvm/x86.c | 2 +-
arch/x86/kvm/x86.h | 5 +++++
3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 72674b8825c4..6ac6312c4d57 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3640,7 +3640,7 @@ static int snp_begin_psc_msr(struct vcpu_svm *svm, u64 ghcb_msr)
return 1; /* resume guest */
}

- if (!(vcpu->kvm->arch.hypercall_exit_enabled & (1 << KVM_HC_MAP_GPA_RANGE))) {
+ if (!user_exit_on_hypercall(vcpu->kvm, KVM_HC_MAP_GPA_RANGE)) {
set_ghcb_msr(svm, GHCB_MSR_PSC_RESP_ERROR);
return 1; /* resume guest */
}
@@ -3723,7 +3723,7 @@ static int snp_begin_psc(struct vcpu_svm *svm, struct psc_buffer *psc)
bool huge;
u64 gfn;

- if (!(vcpu->kvm->arch.hypercall_exit_enabled & (1 << KVM_HC_MAP_GPA_RANGE))) {
+ if (!user_exit_on_hypercall(vcpu->kvm, KVM_HC_MAP_GPA_RANGE)) {
snp_complete_psc(svm, VMGEXIT_PSC_ERROR_GENERIC);
return 1;
}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0b2fe4aa04a2..13fe5d6eb8f3 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10041,7 +10041,7 @@ unsigned long __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr,
u64 gpa = a0, npages = a1, attrs = a2;

ret = -KVM_ENOSYS;
- if (!(vcpu->kvm->arch.hypercall_exit_enabled & (1 << KVM_HC_MAP_GPA_RANGE)))
+ if (!user_exit_on_hypercall(vcpu->kvm, KVM_HC_MAP_GPA_RANGE))
break;

if (!PAGE_ALIGNED(gpa) || !npages ||
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index ec623d23d13d..45dd53284dbd 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -612,4 +612,9 @@ int kvm_sev_es_string_io(struct kvm_vcpu *vcpu, unsigned int size,
unsigned int port, void *data, unsigned int count,
int in);

+static inline bool user_exit_on_hypercall(struct kvm *kvm, unsigned long hc_nr)
+{
+ return kvm->arch.hypercall_exit_enabled & BIT(hc_nr);
+}
+
#endif
--
2.47.0.338.g60cca15819-goog