linux-kernel - RE: [PATCH] KVM: vmx: fix a build warning in hv_enable_direct

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Date:   Wed, 25 Sep 2019 09:03:43 +0000
From:   Tianyu Lan <Tianyu.Lan@...rosoft.com>
To:     vkuznets <vkuznets@...hat.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Jim Mattson <jmattson@...gle.com>
Subject: RE: [PATCH] KVM: vmx: fix a build warning in
 hv_enable_direct_tlbflush() on i386

There is another warning in the report.

arch/x86/kvm/vmx/vmx.c: In function 'hv_enable_direct_tlbflush':
arch/x86/kvm/vmx/vmx.c:507:20: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
  evmcs->hv_vm_id = (u64)vcpu->kvm;
                    ^
The following change can fix it.
-       evmcs->hv_vm_id = (u64)vcpu->kvm;
+       evmcs->hv_vm_id = (unsigned long)vcpu->kvm;
        evmcs->hv_enlightenments_control.nested_flush_hypercall = 1;

-----Original Message-----
From: Vitaly Kuznetsov <vkuznets@...hat.com> 
Sent: Wednesday, September 25, 2019 4:53 PM
To: kvm@...r.kernel.org
Cc: linux-kernel@...r.kernel.org; Paolo Bonzini <pbonzini@...hat.com>; Radim Krčmář <rkrcmar@...hat.com>; Sean Christopherson <sean.j.christopherson@...el.com>; Jim Mattson <jmattson@...gle.com>; Tianyu Lan <Tianyu.Lan@...rosoft.com>
Subject: [PATCH] KVM: vmx: fix a build warning in hv_enable_direct_tlbflush() on i386

The following was reported on i386:

  arch/x86/kvm/vmx/vmx.c: In function 'hv_enable_direct_tlbflush':
  arch/x86/kvm/vmx/vmx.c:503:10: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]

The particular pr_debug() causing it is more or less useless, let's just remove it. Also, simplify the condition a little bit.

Reported-by: kbuild test robot <lkp@...el.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/kvm/vmx/vmx.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index a7c9922e3905..812553b7270f 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -495,13 +495,11 @@ static int hv_enable_direct_tlbflush(struct kvm_vcpu *vcpu)
 	 * Synthetic VM-Exit is not enabled in current code and so All
 	 * evmcs in singe VM shares same assist page.
 	 */
-	if (!*p_hv_pa_pg) {
+	if (!*p_hv_pa_pg)
 		*p_hv_pa_pg = kzalloc(PAGE_SIZE, GFP_KERNEL);
-		if (!*p_hv_pa_pg)
-			return -ENOMEM;
-		pr_debug("KVM: Hyper-V: allocated PA_PG for %llx\n",
-		       (u64)&vcpu->kvm);
-	}
+
+	if (!*p_hv_pa_pg)
+		return -ENOMEM;
 
 	evmcs = (struct hv_enlightened_vmcs *)to_vmx(vcpu)->loaded_vmcs->vmcs;
 
--
2.20.1