linux-kernel - [PATCH v6 1/4] KVM: x86: xen_hvm

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Date:   Wed, 23 Sep 2020 00:10:22 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Joerg Roedel <joro@...tes.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, Jim Mattson <jmattson@...gle.com>,
        x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH v6 1/4] KVM: x86: xen_hvm_config: cleanup return values

Return 1 on errors that are caused by wrong guest behavior
(which will inject #GP to the guest)

And return a negative error value on issues that are
the kernel's fault (e.g -ENOMEM)

Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/kvm/x86.c | 23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 17f4995e80a7e..063d70e736f7f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2694,24 +2694,19 @@ static int xen_hvm_config(struct kvm_vcpu *vcpu, u64 data)
 	u32 page_num = data & ~PAGE_MASK;
 	u64 page_addr = data & PAGE_MASK;
 	u8 *page;
-	int r;
 
-	r = -E2BIG;
 	if (page_num >= blob_size)
-		goto out;
-	r = -ENOMEM;
+		return 1;
+
 	page = memdup_user(blob_addr + (page_num * PAGE_SIZE), PAGE_SIZE);
-	if (IS_ERR(page)) {
-		r = PTR_ERR(page);
-		goto out;
+	if (IS_ERR(page))
+		return PTR_ERR(page);
+
+	if (kvm_vcpu_write_guest(vcpu, page_addr, page, PAGE_SIZE)) {
+		kfree(page);
+		return 1;
 	}
-	if (kvm_vcpu_write_guest(vcpu, page_addr, page, PAGE_SIZE))
-		goto out_free;
-	r = 0;
-out_free:
-	kfree(page);
-out:
-	return r;
+	return 0;
 }
 
 static inline bool kvm_pv_async_pf_enabled(struct kvm_vcpu *vcpu)
-- 
2.26.2