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From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] KVM: x86: Fix warning due to implicit truncation on 32-bit KVM
Date: Wed,  4 Mar 2020 16:24:22 -0800	[thread overview]
Message-ID: <20200305002422.20968-1-sean.j.christopherson@intel.com> (raw)

Explicitly cast the integer literal to an unsigned long when stuffing a
non-canonical value into the host virtual address during private memslot
deletion.  The explicit cast fixes a warning that gets promoted to an
error when running with KVM's newfangled -Werror setting.

  arch/x86/kvm/x86.c:9739:9: error: large integer implicitly truncated
  to unsigned type [-Werror=overflow]

Fixes: a3e967c0b87d3 ("KVM: Terminate memslot walks via used_slots"
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kvm/x86.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ba4d476b79ad..fa03f31ab33c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9735,8 +9735,12 @@ int __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, u32 size)
 		if (!slot || !slot->npages)
 			return 0;
 
-		/* Stuff a non-canonical value to catch use-after-delete. */
-		hva = 0xdeadull << 48;
+		/*
+		 * Stuff a non-canonical value to catch use-after-delete.  This
+		 * ends up being 0 on 32-bit KVM, but there's no better
+		 * alternative.
+		 */
+		hva = (unsigned long)(0xdeadull << 48);
 		old_npages = slot->npages;
 	}
 
-- 
2.24.1


             reply	other threads:[~2020-03-05  0:24 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-05  0:24 Sean Christopherson [this message]
2020-03-05 10:00 ` [PATCH] KVM: x86: Fix warning due to implicit truncation on 32-bit KVM Vitaly Kuznetsov
2020-03-05 16:04   ` Sean Christopherson
2020-03-05 14:29 ` Paolo Bonzini

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