linux-kernel - [PATCH] KVM: VMX: Check the corresponding bits according to the intel sdm

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Date:   Tue, 23 Mar 2021 10:37:26 +0800
From:   lihaiwei.kernel@...il.com
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     pbonzini@...hat.com, seanjc@...gle.com, vkuznets@...hat.com,
        wanpengli@...cent.com, jmattson@...gle.com, joro@...tes.org,
        Haiwei Li <lihaiwei@...cent.com>
Subject: [PATCH] KVM: VMX: Check the corresponding bits according to the intel sdm

From: Haiwei Li <lihaiwei@...cent.com>

According to IA-32 SDM Vol.3D "A.1 BASIC VMX INFORMATION", two inspections
are missing.
* Bit 31 is always 0. Earlier versions of this manual specified that the
VMCS revision identifier was a 32-bit field in bits 31:0 of this MSR. For
all processors produced prior to this change, bit 31 of this MSR was read
as 0.
* The values of bits 47:45 and bits 63:57 are reserved and are read as 0.

Signed-off-by: Haiwei Li <lihaiwei@...cent.com>
---
 arch/x86/kvm/vmx/vmx.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 32cf828..0d6d13c 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2577,6 +2577,20 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
 
 	rdmsr(MSR_IA32_VMX_BASIC, vmx_msr_low, vmx_msr_high);
 
+	/*
+	 * IA-32 SDM Vol 3D: Bit 31 is always 0.
+	 * For all earlier processors, bit 31 of this MSR was read as 0.
+	 */
+	if (vmx_msr_low & (1u<<31))
+		return -EIO;
+
+	/*
+	 * IA-32 SDM Vol 3D: bits 47:45 and bits 63:57 are reserved and are read
+	 * as 0.
+	 */
+	if (vmx_msr_high & 0xfe00e000)
+		return -EIO;
+
 	/* IA-32 SDM Vol 3B: VMCS size is never greater than 4kB. */
 	if ((vmx_msr_high & 0x1fff) > PAGE_SIZE)
 		return -EIO;
-- 
1.8.3.1