diff mbox series

[v4,2/4] KVM: x86: implement emul_is_noncanonical_address using is_noncanonical_address

Message ID 20240906221824.491834-3-mlevitsk@redhat.com (mailing list archive)
State New, archived
Headers show
Series Relax canonical checks on some arch msrs | expand

Commit Message

Maxim Levitsky Sept. 6, 2024, 10:18 p.m. UTC 
Implement the emul_is_noncanonical_address() using
is_noncanonical_address().

This will allow to extend the is_noncanonical_address() to support
different flavors of canonical checks.

Also add X86EMUL_F_MSR and X86EMUL_F_DT_LOAD emulation flags which will be
used to indicate an emulation of a msr or a segment base load, which
will affect the required canonical check.

No functional change is intended.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
 arch/x86/kvm/emulate.c     | 15 +++++++++------
 arch/x86/kvm/kvm_emulate.h |  5 +++++
 arch/x86/kvm/x86.c         |  7 +++++++
 3 files changed, 21 insertions(+), 6 deletions(-)

Comments

Sean Christopherson Oct. 31, 2024, 12:44 a.m. UTC | #1 
On Fri, Sep 06, 2024, Maxim Levitsky wrote:
> Implement the emul_is_noncanonical_address() using
> is_noncanonical_address().
> 
> This will allow to extend the is_noncanonical_address() to support
> different flavors of canonical checks.
> 
> Also add X86EMUL_F_MSR and X86EMUL_F_DT_LOAD emulation flags which will be
> used to indicate an emulation of a msr or a segment base load, which
> will affect the required canonical check.

Adding the flags belongs in a separate patch, there's no reason to squeeze them
into this patch.  Just an FYI, I'll split/fixup when applying.
diff mbox series

Patch

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index e72aed25d7212..8c8061884a019 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -651,9 +651,10 @@  static inline u8 ctxt_virt_addr_bits(struct x86_emulate_ctxt *ctxt)
 }
 
 static inline bool emul_is_noncanonical_address(u64 la,
-						struct x86_emulate_ctxt *ctxt)
+						struct x86_emulate_ctxt *ctxt,
+						unsigned int flags)
 {
-	return !__is_canonical_address(la, ctxt_virt_addr_bits(ctxt));
+	return !ctxt->ops->is_canonical_addr(ctxt, la, 0);
 }
 
 /*
@@ -1733,7 +1734,8 @@  static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
 		if (ret != X86EMUL_CONTINUE)
 			return ret;
 		if (emul_is_noncanonical_address(get_desc_base(&seg_desc) |
-						 ((u64)base3 << 32), ctxt))
+						 ((u64)base3 << 32), ctxt,
+						 X86EMUL_F_DT_LOAD))
 			return emulate_gp(ctxt, err_code);
 	}
 
@@ -2516,8 +2518,8 @@  static int em_sysexit(struct x86_emulate_ctxt *ctxt)
 		ss_sel = cs_sel + 8;
 		cs.d = 0;
 		cs.l = 1;
-		if (emul_is_noncanonical_address(rcx, ctxt) ||
-		    emul_is_noncanonical_address(rdx, ctxt))
+		if (emul_is_noncanonical_address(rcx, ctxt, 0) ||
+		    emul_is_noncanonical_address(rdx, ctxt, 0))
 			return emulate_gp(ctxt, 0);
 		break;
 	}
@@ -3494,7 +3496,8 @@  static int em_lgdt_lidt(struct x86_emulate_ctxt *ctxt, bool lgdt)
 	if (rc != X86EMUL_CONTINUE)
 		return rc;
 	if (ctxt->mode == X86EMUL_MODE_PROT64 &&
-	    emul_is_noncanonical_address(desc_ptr.address, ctxt))
+	    emul_is_noncanonical_address(desc_ptr.address, ctxt,
+					 X86EMUL_F_DT_LOAD))
 		return emulate_gp(ctxt, 0);
 	if (lgdt)
 		ctxt->ops->set_gdt(ctxt, &desc_ptr);
diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h
index 55a18e2f2dcd9..86bde1c9d9183 100644
--- a/arch/x86/kvm/kvm_emulate.h
+++ b/arch/x86/kvm/kvm_emulate.h
@@ -94,6 +94,8 @@  struct x86_instruction_info {
 #define X86EMUL_F_FETCH			BIT(1)
 #define X86EMUL_F_IMPLICIT		BIT(2)
 #define X86EMUL_F_INVLPG		BIT(3)
+#define X86EMUL_F_MSR			BIT(4)
+#define X86EMUL_F_DT_LOAD		BIT(5)
 
 struct x86_emulate_ops {
 	void (*vm_bugged)(struct x86_emulate_ctxt *ctxt);
@@ -235,6 +237,9 @@  struct x86_emulate_ops {
 
 	gva_t (*get_untagged_addr)(struct x86_emulate_ctxt *ctxt, gva_t addr,
 				   unsigned int flags);
+
+	bool (*is_canonical_addr)(struct x86_emulate_ctxt *ctxt,
+				  gva_t addr, unsigned int flags);
 };
 
 /* Type, address-of, and value of an instruction's operand. */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f72e5d89e942d..f496830445355 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8617,6 +8617,12 @@  static gva_t emulator_get_untagged_addr(struct x86_emulate_ctxt *ctxt,
 					       addr, flags);
 }
 
+static bool emulator_is_canonical_addr(struct x86_emulate_ctxt *ctxt,
+				       gva_t addr, unsigned int flags)
+{
+	return !is_noncanonical_address(addr, emul_to_vcpu(ctxt));
+}
+
 static const struct x86_emulate_ops emulate_ops = {
 	.vm_bugged           = emulator_vm_bugged,
 	.read_gpr            = emulator_read_gpr,
@@ -8663,6 +8669,7 @@  static const struct x86_emulate_ops emulate_ops = {
 	.triple_fault        = emulator_triple_fault,
 	.set_xcr             = emulator_set_xcr,
 	.get_untagged_addr   = emulator_get_untagged_addr,
+	.is_canonical_addr   = emulator_is_canonical_addr,
 };
 
 static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask)