Commit Message

Stefan Bader Aug. 3, 2012, 10:55 a.m. UTC

Subject: Re: Nested kvm_intel broken on pre 3.3 hosts

> No, you're backporting the entire feature.  All we need is to expose
> RDPMC intercept to the guest.

Oh well, I thought that was the thing you asked for...

> It should be sufficient to backport the bits in
> nested_vmx_setup_ctls_msrs() and nested_vmx_exit_handled().

Ok, how about that? It is probably wrong again, but at least it
allows to load the kvm-intel module from within a nested guest
and not having the feature pretend to fail seems the closest
thing to do...

---

From 0aeb99348363b7aeb2b0bd92428cb212159fa468 Mon Sep 17 00:00:00 2001
From: Stefan Bader <[e-mail]>
Date: Thu, 10 Nov 2011 14:57:25 +0200
Subject: [PATCH] KVM: VMX: Fake intercept RDPMC

Based on commit fee84b079d5ddee2247b5c1f53162c330c622902 upstream.

  Intercept RDPMC and forward it to the PMU emulation code.

But drop the requirement for the feature being present and instead
of forwarding, cause a GP as if the call had failed.

BugLink: http://bugs.launchpad.net/bugs/1031090
Signed-off-by: Stefan Bader <[e-mail]>
---
 arch/x86/kvm/vmx.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

Patch

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 7315488..fc937f2 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1956,6 +1956,7 @@  static __init void nested_vmx_setup_ctls_msrs(void)
 #endif
 		CPU_BASED_MOV_DR_EXITING | CPU_BASED_UNCOND_IO_EXITING |
 		CPU_BASED_USE_IO_BITMAPS | CPU_BASED_MONITOR_EXITING |
+		CPU_BASED_RDPMC_EXITING |
 		CPU_BASED_ACTIVATE_SECONDARY_CONTROLS;
 	/*
 	 * We can allow some features even when not supported by the
@@ -4613,6 +4614,14 @@  static int handle_invlpg(struct kvm_vcpu *vcpu)
 	return 1;
 }
 
+static int handle_rdpmc(struct kvm_vcpu *vcpu)
+{
+	/* Instead of implementing the feature, cause a GP */
+	kvm_complete_insn_gp(vcpu, 1);
+
+	return 1;
+}
+
 static int handle_wbinvd(struct kvm_vcpu *vcpu)
 {
 	skip_emulated_instruction(vcpu);
@@ -5563,6 +5572,7 @@  static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
 	[EXIT_REASON_HLT]                     = handle_halt,
 	[EXIT_REASON_INVD]		      = handle_invd,
 	[EXIT_REASON_INVLPG]		      = handle_invlpg,
+	[EXIT_REASON_RDPMC]                   = handle_rdpmc,
 	[EXIT_REASON_VMCALL]                  = handle_vmcall,
 	[EXIT_REASON_VMCLEAR]	              = handle_vmclear,
 	[EXIT_REASON_VMLAUNCH]                = handle_vmlaunch,