linux-kernel - [PATCH 1/2] KVM: x86: Check hypercall's exit to userspace generically

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Message-ID: <20240708092150.1799371-2-binbin.wu@linux.intel.com>
Date: Mon,  8 Jul 2024 17:21:49 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: pbonzini@...hat.com,
	seanjc@...gle.com,
	isaku.yamahata@...el.com,
	michael.roth@....com,
	binbin.wu@...ux.intel.com
Subject: [PATCH 1/2] KVM: x86: Check hypercall's exit to userspace generically

Check whether a KVM hypercall needs to exit to userspace or not based on
hypercall_exit_enabled field of struct kvm_arch.

Userspace can request a hypercall to exit to userspace for handling by
enable KVM_CAP_EXIT_HYPERCALL and the enabled hypercall will be set in
hypercall_exit_enabled.  Make the check code generic based on it.

Signed-off-by: Binbin Wu <binbin.wu@...ux.intel.com>
---
 arch/x86/kvm/x86.c | 4 ++--
 arch/x86/kvm/x86.h | 4 ++++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 994743266480..f84c1f263e9b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10223,8 +10223,8 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
 	cpl = kvm_x86_call(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. */
+	if (is_kvm_hc_exit_enabled(vcpu->kvm, nr) && !ret)
+		/* The hypercall is requested to exit to userspace. */
 		return 0;
 
 	if (!op_64_bit)
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 50596f6f8320..02809a915d72 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -547,4 +547,8 @@ 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 is_kvm_hc_exit_enabled(struct kvm *kvm, unsigned long hc_nr)
+{
+	return kvm->arch.hypercall_exit_enabled & (1 << hc_nr);
+}
 #endif
-- 
2.43.2