KVM: MMU: introduce rsvd_bits_validate

These two fields, rsvd_bits_mask and bad_mt_xwr, in "struct kvm_mmu" are
used to check if reserved bits set on guest ptes, move them to a data
struct so that the approach can be applied to check host shadow page
table entries as well

Signed-off-by: Xiao Guangrong <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

Author: Xiao Guangrong

arch/x86/include/asm/kvm_host.h

@@ -252,6 +252,11 @@ struct kvm_pio_request {
 	int size;
 };
 
+struct rsvd_bits_validate {
+	u64 rsvd_bits_mask[2][4];
+	u64 bad_mt_xwr;
+};
+
 /*
  * x86 supports 3 paging modes (4-level 64-bit, 3-level 64-bit, and 2-level
  * 32-bit).  The kvm_mmu structure abstracts the details of the current mmu
@@ -289,8 +294,7 @@ struct kvm_mmu {
 
 	u64 *pae_root;
 	u64 *lm_root;
-	u64 rsvd_bits_mask[2][4];
-	u64 bad_mt_xwr;
+	struct rsvd_bits_validate guest_rsvd_check;
 
 	/*
 	 * Bitmap: bit set = last pte in walk

arch/x86/kvm/mmu.c

@@ -3548,10 +3548,11 @@ static inline bool is_last_gpte(struct kvm_mmu *mmu, unsigned level, unsigned gp
 
 static bool is_rsvd_bits_set(struct kvm_mmu *mmu, u64 gpte, int level)
 {
+	struct rsvd_bits_validate *rsvd_check = &mmu->guest_rsvd_check;
 	int bit7 = (gpte >> 7) & 1, low6 = gpte & 0x3f;
 
-	return (gpte & mmu->rsvd_bits_mask[bit7][level-1]) |
-		((mmu->bad_mt_xwr & (1ull << low6)) != 0);
+	return (gpte & rsvd_check->rsvd_bits_mask[bit7][level-1]) |
+		((rsvd_check->bad_mt_xwr & (1ull << low6)) != 0);
 }
 
 #define PTTYPE_EPT 18 /* arbitrary */
@@ -3570,12 +3571,13 @@ static bool is_rsvd_bits_set(struct kvm_mmu *mmu, u64 gpte, int level)
 static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu,
 				  struct kvm_mmu *context)
 {
+	struct rsvd_bits_validate *rsvd_check = &context->guest_rsvd_check;
 	int maxphyaddr = cpuid_maxphyaddr(vcpu);
 	u64 exb_bit_rsvd = 0;
 	u64 gbpages_bit_rsvd = 0;
 	u64 nonleaf_bit8_rsvd = 0;
 
-	context->bad_mt_xwr = 0;
+	rsvd_check->bad_mt_xwr = 0;
 
 	if (!context->nx)
 		exb_bit_rsvd = rsvd_bits(63, 63);
@@ -3592,85 +3594,92 @@ static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu,
 	switch (context->root_level) {
 	case PT32_ROOT_LEVEL:
 		/* no rsvd bits for 2 level 4K page table entries */
-		context->rsvd_bits_mask[0][1] = 0;
-		context->rsvd_bits_mask[0][0] = 0;
-		context->rsvd_bits_mask[1][0] = context->rsvd_bits_mask[0][0];
+		rsvd_check->rsvd_bits_mask[0][1] = 0;
+		rsvd_check->rsvd_bits_mask[0][0] = 0;
+		rsvd_check->rsvd_bits_mask[1][0] =
+			rsvd_check->rsvd_bits_mask[0][0];
 
 		if (!is_pse(vcpu)) {
-			context->rsvd_bits_mask[1][1] = 0;
+			rsvd_check->rsvd_bits_mask[1][1] = 0;
 			break;
 		}
 
 		if (is_cpuid_PSE36())
 			/* 36bits PSE 4MB page */
-			context->rsvd_bits_mask[1][1] = rsvd_bits(17, 21);
+			rsvd_check->rsvd_bits_mask[1][1] = rsvd_bits(17, 21);
 		else
 			/* 32 bits PSE 4MB page */
-			context->rsvd_bits_mask[1][1] = rsvd_bits(13, 21);
+			rsvd_check->rsvd_bits_mask[1][1] = rsvd_bits(13, 21);
 		break;
 	case PT32E_ROOT_LEVEL:
-		context->rsvd_bits_mask[0][2] =
+		rsvd_check->rsvd_bits_mask[0][2] =
 			rsvd_bits(maxphyaddr, 63) |
 			rsvd_bits(5, 8) | rsvd_bits(1, 2);	/* PDPTE */
-		context->rsvd_bits_mask[0][1] = exb_bit_rsvd |
+		rsvd_check->rsvd_bits_mask[0][1] = exb_bit_rsvd |
 			rsvd_bits(maxphyaddr, 62);	/* PDE */
-		context->rsvd_bits_mask[0][0] = exb_bit_rsvd |
+		rsvd_check->rsvd_bits_mask[0][0] = exb_bit_rsvd |
 			rsvd_bits(maxphyaddr, 62); 	/* PTE */
-		context->rsvd_bits_mask[1][1] = exb_bit_rsvd |
+		rsvd_check->rsvd_bits_mask[1][1] = exb_bit_rsvd |
 			rsvd_bits(maxphyaddr, 62) |
 			rsvd_bits(13, 20);		/* large page */
-		context->rsvd_bits_mask[1][0] = context->rsvd_bits_mask[0][0];
+		rsvd_check->rsvd_bits_mask[1][0] =
+			rsvd_check->rsvd_bits_mask[0][0];
 		break;
 	case PT64_ROOT_LEVEL:
-		context->rsvd_bits_mask[0][3] = exb_bit_rsvd |
-			nonleaf_bit8_rsvd | rsvd_bits(7, 7) | rsvd_bits(maxphyaddr, 51);
-		context->rsvd_bits_mask[0][2] = exb_bit_rsvd |
-			nonleaf_bit8_rsvd | gbpages_bit_rsvd | rsvd_bits(maxphyaddr, 51);
-		context->rsvd_bits_mask[0][1] = exb_bit_rsvd |
+		rsvd_check->rsvd_bits_mask[0][3] = exb_bit_rsvd |
+			nonleaf_bit8_rsvd | rsvd_bits(7, 7) |
 			rsvd_bits(maxphyaddr, 51);
-		context->rsvd_bits_mask[0][0] = exb_bit_rsvd |
+		rsvd_check->rsvd_bits_mask[0][2] = exb_bit_rsvd |
+			nonleaf_bit8_rsvd | gbpages_bit_rsvd |
 			rsvd_bits(maxphyaddr, 51);
-		context->rsvd_bits_mask[1][3] = context->rsvd_bits_mask[0][3];
-		context->rsvd_bits_mask[1][2] = exb_bit_rsvd |
+		rsvd_check->rsvd_bits_mask[0][1] = exb_bit_rsvd |
+			rsvd_bits(maxphyaddr, 51);
+		rsvd_check->rsvd_bits_mask[0][0] = exb_bit_rsvd |
+			rsvd_bits(maxphyaddr, 51);
+		rsvd_check->rsvd_bits_mask[1][3] =
+			rsvd_check->rsvd_bits_mask[0][3];
+		rsvd_check->rsvd_bits_mask[1][2] = exb_bit_rsvd |
 			gbpages_bit_rsvd | rsvd_bits(maxphyaddr, 51) |
 			rsvd_bits(13, 29);
-		context->rsvd_bits_mask[1][1] = exb_bit_rsvd |
+		rsvd_check->rsvd_bits_mask[1][1] = exb_bit_rsvd |
 			rsvd_bits(maxphyaddr, 51) |
 			rsvd_bits(13, 20);		/* large page */
-		context->rsvd_bits_mask[1][0] = context->rsvd_bits_mask[0][0];
+		rsvd_check->rsvd_bits_mask[1][0] =
+			rsvd_check->rsvd_bits_mask[0][0];
 		break;
 	}
 }
 
 static void reset_rsvds_bits_mask_ept(struct kvm_vcpu *vcpu,
 		struct kvm_mmu *context, bool execonly)
 {
+	struct rsvd_bits_validate *rsvd_check = &context->guest_rsvd_check;
 	int maxphyaddr = cpuid_maxphyaddr(vcpu);
 	int pte;
 
-	context->rsvd_bits_mask[0][3] =
+	rsvd_check->rsvd_bits_mask[0][3] =
 		rsvd_bits(maxphyaddr, 51) | rsvd_bits(3, 7);
-	context->rsvd_bits_mask[0][2] =
+	rsvd_check->rsvd_bits_mask[0][2] =
 		rsvd_bits(maxphyaddr, 51) | rsvd_bits(3, 6);
-	context->rsvd_bits_mask[0][1] =
+	rsvd_check->rsvd_bits_mask[0][1] =
 		rsvd_bits(maxphyaddr, 51) | rsvd_bits(3, 6);
-	context->rsvd_bits_mask[0][0] = rsvd_bits(maxphyaddr, 51);
+	rsvd_check->rsvd_bits_mask[0][0] = rsvd_bits(maxphyaddr, 51);
 
 	/* large page */
-	context->rsvd_bits_mask[1][3] = context->rsvd_bits_mask[0][3];
-	context->rsvd_bits_mask[1][2] =
+	rsvd_check->rsvd_bits_mask[1][3] = rsvd_check->rsvd_bits_mask[0][3];
+	rsvd_check->rsvd_bits_mask[1][2] =
 		rsvd_bits(maxphyaddr, 51) | rsvd_bits(12, 29);
-	context->rsvd_bits_mask[1][1] =
+	rsvd_check->rsvd_bits_mask[1][1] =
 		rsvd_bits(maxphyaddr, 51) | rsvd_bits(12, 20);
-	context->rsvd_bits_mask[1][0] = context->rsvd_bits_mask[0][0];
+	rsvd_check->rsvd_bits_mask[1][0] = rsvd_check->rsvd_bits_mask[0][0];
 
 	for (pte = 0; pte < 64; pte++) {
 		int rwx_bits = pte & 7;
 		int mt = pte >> 3;
 		if (mt == 0x2 || mt == 0x3 || mt == 0x7 ||
 				rwx_bits == 0x2 || rwx_bits == 0x6 ||
 				(rwx_bits == 0x4 && !execonly))
-			context->bad_mt_xwr |= (1ull << pte);
+			rsvd_check->bad_mt_xwr |= (1ull << pte);
 	}
 }
 

arch/x86/kvm/x86.c

@@ -525,7 +525,8 @@ int load_pdptrs(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, unsigned long cr3)
 	}
 	for (i = 0; i < ARRAY_SIZE(pdpte); ++i) {
 		if (is_present_gpte(pdpte[i]) &&
-		    (pdpte[i] & vcpu->arch.mmu.rsvd_bits_mask[0][2])) {
+		    (pdpte[i] &
+		     vcpu->arch.mmu.guest_rsvd_check.rsvd_bits_mask[0][2])) {
 			ret = 0;
 			goto out;
 		}