Re: [PATCH v2 07/30] KVM: Provide x86_emulate_ctxt callback to get current cpl

[Gleb Natapov <gleb@redhat.com>]

On Mon, Mar 15, 2010 at 02:16:01PM +0100, Andre Przywara wrote:
> Gleb,
> 
> what is the purpose of this patch? Is this a preparation for
> something upcoming? I don't see a reason to change this, in my eyes
> it is not a simplification.
> 
To make emulator independent of KVM. All direct calls from emulator to
KVM will be changed to callbacks.

> Regards,
> Andre.
> 
> 
> Gleb Natapov wrote:
> >Signed-off-by: Gleb Natapov <gleb@redhat.com>
> >---
> > arch/x86/include/asm/kvm_emulate.h |    1 +
> > arch/x86/kvm/emulate.c             |   15 ++++++++-------
> > arch/x86/kvm/x86.c                 |    6 ++++++
> > 3 files changed, 15 insertions(+), 7 deletions(-)
> >
> >diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
> >index 0c5caa4..b048fd2 100644
> >--- a/arch/x86/include/asm/kvm_emulate.h
> >+++ b/arch/x86/include/asm/kvm_emulate.h
> >@@ -110,6 +110,7 @@ struct x86_emulate_ops {
> > 				struct kvm_vcpu *vcpu);
> > 	ulong (*get_cr)(int cr, struct kvm_vcpu *vcpu);
> > 	void (*set_cr)(int cr, ulong val, struct kvm_vcpu *vcpu);
> >+	int (*cpl)(struct kvm_vcpu *vcpu);
> > };
> > /* Type, address-of, and value of an instruction's operand. */
> >diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> >index 5e2fa61..8bd0557 100644
> >--- a/arch/x86/kvm/emulate.c
> >+++ b/arch/x86/kvm/emulate.c
> >@@ -1257,7 +1257,7 @@ static int emulate_popf(struct x86_emulate_ctxt *ctxt,
> > 	int rc;
> > 	unsigned long val, change_mask;
> > 	int iopl = (ctxt->eflags & X86_EFLAGS_IOPL) >> IOPL_SHIFT;
> >-	int cpl = kvm_x86_ops->get_cpl(ctxt->vcpu);
> >+	int cpl = ops->cpl(ctxt->vcpu);
> > 	rc = emulate_pop(ctxt, ops, &val, len);
> > 	if (rc != X86EMUL_CONTINUE)
> >@@ -1758,7 +1758,8 @@ emulate_sysexit(struct x86_emulate_ctxt *ctxt)
> > 	return X86EMUL_CONTINUE;
> > }
> >-static bool emulator_bad_iopl(struct x86_emulate_ctxt *ctxt)
> >+static bool emulator_bad_iopl(struct x86_emulate_ctxt *ctxt,
> >+			      struct x86_emulate_ops *ops)
> > {
> > 	int iopl;
> > 	if (ctxt->mode == X86EMUL_MODE_REAL)
> >@@ -1766,7 +1767,7 @@ static bool emulator_bad_iopl(struct x86_emulate_ctxt *ctxt)
> > 	if (ctxt->mode == X86EMUL_MODE_VM86)
> > 		return true;
> > 	iopl = (ctxt->eflags & X86_EFLAGS_IOPL) >> IOPL_SHIFT;
> >-	return kvm_x86_ops->get_cpl(ctxt->vcpu) > iopl;
> >+	return ops->cpl(ctxt->vcpu) > iopl;
> > }
> > static bool emulator_io_port_access_allowed(struct x86_emulate_ctxt *ctxt,
> >@@ -1803,7 +1804,7 @@ static bool emulator_io_permited(struct x86_emulate_ctxt *ctxt,
> > 				 struct x86_emulate_ops *ops,
> > 				 u16 port, u16 len)
> > {
> >-	if (emulator_bad_iopl(ctxt))
> >+	if (emulator_bad_iopl(ctxt, ops))
> > 		if (!emulator_io_port_access_allowed(ctxt, ops, port, len))
> > 			return false;
> > 	return true;
> >@@ -1842,7 +1843,7 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
> > 	}
> > 	/* Privileged instruction can be executed only in CPL=0 */
> >-	if ((c->d & Priv) && kvm_x86_ops->get_cpl(ctxt->vcpu)) {
> >+	if ((c->d & Priv) && ops->cpl(ctxt->vcpu)) {
> > 		kvm_inject_gp(ctxt->vcpu, 0);
> > 		goto done;
> > 	}
> >@@ -2378,7 +2379,7 @@ special_insn:
> > 		c->dst.type = OP_NONE;	/* Disable writeback. */
> > 		break;
> > 	case 0xfa: /* cli */
> >-		if (emulator_bad_iopl(ctxt))
> >+		if (emulator_bad_iopl(ctxt, ops))
> > 			kvm_inject_gp(ctxt->vcpu, 0);
> > 		else {
> > 			ctxt->eflags &= ~X86_EFLAGS_IF;
> >@@ -2386,7 +2387,7 @@ special_insn:
> > 		}
> > 		break;
> > 	case 0xfb: /* sti */
> >-		if (emulator_bad_iopl(ctxt))
> >+		if (emulator_bad_iopl(ctxt, ops))
> > 			kvm_inject_gp(ctxt->vcpu, 0);
> > 		else {
> > 			toggle_interruptibility(ctxt, KVM_X86_SHADOW_INT_STI);
> >diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> >index b08f8a1..3f2a8d3 100644
> >--- a/arch/x86/kvm/x86.c
> >+++ b/arch/x86/kvm/x86.c
> >@@ -3426,6 +3426,11 @@ static void emulator_set_cr(int cr, unsigned long val, struct kvm_vcpu *vcpu)
> > 	}
> > }
> >+static int emulator_get_cpl(struct kvm_vcpu *vcpu)
> >+{
> >+	return kvm_x86_ops->get_cpl(vcpu);
> >+}
> >+
> > static struct x86_emulate_ops emulate_ops = {
> > 	.read_std            = kvm_read_guest_virt_system,
> > 	.fetch               = kvm_fetch_guest_virt,
> >@@ -3434,6 +3439,7 @@ static struct x86_emulate_ops emulate_ops = {
> > 	.cmpxchg_emulated    = emulator_cmpxchg_emulated,
> > 	.get_cr              = emulator_get_cr,
> > 	.set_cr              = emulator_set_cr,
> >+	.cpl                 = emulator_get_cpl,
> > };
> > static void cache_all_regs(struct kvm_vcpu *vcpu)
> 
> 
> -- 
> Andre Przywara
> AMD-OSRC (Dresden)
> Tel: x29712

--
			Gleb.