On 05.08.2012 11:18, Avi Kivity wrote: > On 08/03/2012 01:57 PM, Stefan Bader wrote: >>> 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... > > Sorry for being unclear. > >> >>> 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 <stefan.bader@xxxxxxxxxxxxx> >> 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 <stefan.bader@xxxxxxxxxxxxx> >> --- >> arch/x86/kvm/vmx.c | 10 ++++++++++ >> 1 file changed, 10 insertions(+) >> >> 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; >> +} > > In fact this should never be called, since we never request RDPMC > exiting for L1. > >> + >> 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, >> > > Provided you backport the bit in nested_vmx_exit_handled(). That takes > the L2->L1 RDPMC exit and forwards it to L1. > The nested_vmx_exit_handled handled function is already there (in 3.1). commit 644d711aa0e16111d8aba6d289caebec013e26ea Author: Nadav Har'El <nyh@xxxxxxxxxx> Date: Wed May 25 23:12:35 2011 +0300 KVM: nVMX: Deciding if L0 or L1 should handle an L2 exit Though I checked what happens if I drop anything beside the change in nested_vmx_setup_ctls_msrs. If running "perf test" (which does some RDPMC test) is sufficient to prove things are ok, then it seems to be good enough. That test fails already on the perf_event_open syscall (returning -ENOENT). So this remaining (attached patch) change would be enough to allow the kvm_intel module get loaded from newer kernels on an 3.2 host.
From b79a5f03b4d9a1a56949d6ef38fd4879ff1b8aee Mon Sep 17 00:00:00 2001 From: Stefan Bader <stefan.bader@xxxxxxxxxxxxx> Date: Thu, 10 Nov 2011 14:57:25 +0200 Subject: [PATCH] KVM: VMX: Set CPU_BASED_RDPMC_EXITING for nested Based on commit fee84b079d5ddee2247b5c1f53162c330c622902 upstream. Intercept RDPMC and forward it to the PMU emulation code. Newer vmx support will only allow to load the kvm_intel module if RDPMC_EXITING is supported. Even without the actual support this part of the change is required on 3.2 hosts. BugLink: http://bugs.launchpad.net/bugs/1031090 Signed-off-by: Stefan Bader <stefan.bader@xxxxxxxxxxxxx> --- arch/x86/kvm/vmx.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 114fe29..94e6749 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -1957,6 +1957,7 @@ 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 -- 1.7.9.5
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