linux-kernel - [RFC PATCH 28/73] KVM: x86/PVM: Handle syscall from user mode

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Date: Mon, 26 Feb 2024 22:35:45 +0800
From: Lai Jiangshan <jiangshanlai@...il.com>
To: linux-kernel@...r.kernel.org
Cc: Lai Jiangshan <jiangshan.ljs@...group.com>,
	Hou Wenlong <houwenlong.hwl@...group.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Sean Christopherson <seanjc@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...en8.de>,
	Ingo Molnar <mingo@...hat.com>,
	kvm@...r.kernel.org,
	Paolo Bonzini <pbonzini@...hat.com>,
	x86@...nel.org,
	Kees Cook <keescook@...omium.org>,
	Juergen Gross <jgross@...e.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: [RFC PATCH 28/73] KVM: x86/PVM: Handle syscall from user mode

From: Lai Jiangshan <jiangshan.ljs@...group.com>

Similar to the vector event from user mode, the syscall event from user
mode follows the PVM event delivery ABI. Additionally, the 32-bit user
mode can only use "INT 0x80" for syscall.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@...group.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@...group.com>
---
 arch/x86/kvm/pvm/pvm.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/pvm/pvm.c b/arch/x86/kvm/pvm/pvm.c
index 57d987903791..92eef226df28 100644
--- a/arch/x86/kvm/pvm/pvm.c
+++ b/arch/x86/kvm/pvm/pvm.c
@@ -915,6 +915,15 @@ static void pvm_setup_mce(struct kvm_vcpu *vcpu)
 {
 }
 
+static int handle_exit_syscall(struct kvm_vcpu *vcpu)
+{
+	struct vcpu_pvm *pvm = to_pvm(vcpu);
+
+	if (!is_smod(pvm))
+		return do_pvm_user_event(vcpu, PVM_SYSCALL_VECTOR, false, 0);
+	return 1;
+}
+
 static int handle_exit_external_interrupt(struct kvm_vcpu *vcpu)
 {
 	++vcpu->stat.irq_exits;
@@ -939,7 +948,11 @@ static int pvm_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
 	struct vcpu_pvm *pvm = to_pvm(vcpu);
 	u32 exit_reason = pvm->exit_vector;
 
-	if (exit_reason >= FIRST_EXTERNAL_VECTOR && exit_reason < NR_VECTORS)
+	if (exit_reason == PVM_SYSCALL_VECTOR)
+		return handle_exit_syscall(vcpu);
+	else if (exit_reason == IA32_SYSCALL_VECTOR)
+		return do_pvm_event(vcpu, IA32_SYSCALL_VECTOR, false, 0);
+	else if (exit_reason >= FIRST_EXTERNAL_VECTOR && exit_reason < NR_VECTORS)
 		return handle_exit_external_interrupt(vcpu);
 	else if (exit_reason == PVM_FAILED_VMENTRY_VECTOR)
 		return handle_exit_failed_vmentry(vcpu);
-- 
2.19.1.6.gb485710b