linux-kernel - [PATCH] KVM/nVMX: Do not validate that posted_intr_desc

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Message-Id: <1540071779-20848-1-git-send-email-karahmed@amazon.de>
Date:   Sat, 20 Oct 2018 23:42:59 +0200
From:   KarimAllah Ahmed <karahmed@...zon.de>
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     KarimAllah Ahmed <karahmed@...zon.de>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org
Subject: [PATCH] KVM/nVMX: Do not validate that posted_intr_desc_addr is page aligned

The spec only requires the posted interrupt descriptor address to be
64-bytes aligned (i.e. bits[0:5] == 0). Using page_address_valid also
forces the address to be page aligned.

Only validate that the address does not cross the maximum physical address
without enforcing a page alignment.

Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: x86@...nel.org
Cc: kvm@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Fixes: 6de84e581c0 ("nVMX x86: check posted-interrupt descriptor addresss on vmentry of L2")
Signed-off-by: KarimAllah Ahmed <karahmed@...zon.de>
---
 arch/x86/kvm/vmx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 30bf860..47962f2 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -11668,7 +11668,7 @@ static int nested_vmx_check_apicv_controls(struct kvm_vcpu *vcpu,
 	    !nested_exit_intr_ack_set(vcpu) ||
 	    (vmcs12->posted_intr_nv & 0xff00) ||
 	    (vmcs12->posted_intr_desc_addr & 0x3f) ||
-	    (!page_address_valid(vcpu, vmcs12->posted_intr_desc_addr))))
+	    (vmcs12->posted_intr_desc_addr >> cpuid_maxphyaddr(vcpu)))
 		return -EINVAL;
 
 	/* tpr shadow is needed by all apicv features. */
-- 
2.7.4