linux-kernel - [PATCH v2 1/2] KVM: x86: Check hypercall's exit to userspace generically

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240813051256.2246612-2-binbin.wu@linux.intel.com>
Date: Tue, 13 Aug 2024 13:12:55 +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,
	rick.p.edgecombe@...el.com,
	michael.roth@....com,
	binbin.wu@...ux.intel.com
Subject: [PATCH v2 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 | 7 +++++++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index af6c8cf6a37a..6e16c9751af7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10226,8 +10226,8 @@ 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 (!ret && is_kvm_hc_exit_enabled(vcpu->kvm, nr))
+		/* 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..0cbec76b42e6 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -547,4 +547,11 @@ 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)
+{
+	if(WARN_ON_ONCE(hc_nr >= sizeof(kvm->arch.hypercall_exit_enabled) * 8))
+		return false;
+
+	return kvm->arch.hypercall_exit_enabled & (1 << hc_nr);
+}
 #endif
-- 
2.43.2