From: Yu Zhang <yu.c.zhang@linux.intel.com>
Date: Thu, 24 Aug 2017 12:27:53 +0000 (+0800)
Subject: KVM: MMU: check guest CR3 reserved bits based on its physical address width.
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=d1cd3ce9004412949163bfaa062a4df98fe75a98;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

KVM: MMU: check guest CR3 reserved bits based on its physical address width.

Currently, KVM uses CR3_L_MODE_RESERVED_BITS to check the
reserved bits in CR3. Yet the length of reserved bits in
guest CR3 should be based on the physical address width
exposed to the VM. This patch changes CR3 check logic to
calculate the reserved bits at runtime.

Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 6db0ed9cf59e..e7162285b22e 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -79,7 +79,6 @@
 			  | X86_CR0_ET | X86_CR0_NE | X86_CR0_WP | X86_CR0_AM \
 			  | X86_CR0_NW | X86_CR0_CD | X86_CR0_PG))
 
-#define CR3_L_MODE_RESERVED_BITS 0xFFFFFF0000000000ULL
 #define CR3_PCID_INVD		 BIT_64(63)
 #define CR4_RESERVED_BITS                                               \
 	(~(unsigned long)(X86_CR4_VME | X86_CR4_PVI | X86_CR4_TSD | X86_CR4_DE\
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 319d91f6f3c4..a89b595dab22 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -28,6 +28,7 @@
 
 #include "x86.h"
 #include "tss.h"
+#include "mmu.h"
 
 /*
  * Operand types
@@ -4097,8 +4098,17 @@ static int check_cr_write(struct x86_emulate_ctxt *ctxt)
 		u64 rsvd = 0;
 
 		ctxt->ops->get_msr(ctxt, MSR_EFER, &efer);
-		if (efer & EFER_LMA)
-			rsvd = CR3_L_MODE_RESERVED_BITS & ~CR3_PCID_INVD;
+		if (efer & EFER_LMA) {
+			u64 maxphyaddr;
+			u32 eax = 0x80000008;
+
+			if (ctxt->ops->get_cpuid(ctxt, &eax, NULL, NULL,
+						 NULL, false))
+				maxphyaddr = eax & 0xff;
+			else
+				maxphyaddr = 36;
+			rsvd = rsvd_bits(maxphyaddr, 62);
+		}
 
 		if (new_val & rsvd)
 			return emulate_gp(ctxt, 0);
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 3ed6192d93b1..67e7ec2eb7e0 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -48,6 +48,9 @@
 
 static inline u64 rsvd_bits(int s, int e)
 {
+	if (e < s)
+		return 0;
+
 	return ((1ULL << (e - s + 1)) - 1) << s;
 }
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index cc2c7e413e9c..79f5889f8c12 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -813,10 +813,10 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
 		return 0;
 	}
 
-	if (is_long_mode(vcpu)) {
-		if (cr3 & CR3_L_MODE_RESERVED_BITS)
-			return 1;
-	} else if (is_pae(vcpu) && is_paging(vcpu) &&
+	if (is_long_mode(vcpu) &&
+	    (cr3 & rsvd_bits(cpuid_maxphyaddr(vcpu), 62)))
+		return 1;
+	else if (is_pae(vcpu) && is_paging(vcpu) &&
 		   !load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3))
 		return 1;