From 9b5e85320fcc3af20ce0397b2c6363b6ee5815b6 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 24 Jan 2020 15:07:22 -0800 Subject: [PATCH] KVM: x86: Take a u64 when checking for a valid dr7 value Take a u64 instead of an unsigned long in kvm_dr7_valid() to fix a build warning on i386 due to right-shifting a 32-bit value by 32 when checking for bits being set in dr7[63:32]. Alternatively, the warning could be resolved by rewriting the check to use an i386-friendly method, but taking a u64 fixes another oddity on 32-bit KVM. Beause KVM implements natural width VMCS fields as u64s to avoid layout issues between 32-bit and 64-bit, a devious guest can stuff vmcs12->guest_dr7 with a 64-bit value even when both the guest and host are 32-bit kernels. KVM eventually drops vmcs12->guest_dr7[63:32] when propagating vmcs12->guest_dr7 to vmcs02, but ideally KVM would not rely on that behavior for correctness. Cc: Jim Mattson Cc: Krish Sadhukhan Fixes: ecb697d10f70 ("KVM: nVMX: Check GUEST_DR7 on vmentry of nested guests") Reported-by: Randy Dunlap Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index 2d2ff85..3624665 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -357,7 +357,7 @@ static inline bool kvm_pat_valid(u64 data) return (data | ((data & 0x0202020202020202ull) << 1)) == data; } -static inline bool kvm_dr7_valid(unsigned long data) +static inline bool kvm_dr7_valid(u64 data) { /* Bits [63:32] are reserved */ return !(data >> 32); -- 2.7.4