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* Re: [RFC 02/10] x86/kvm: Add IBPB support
@ 2018-01-20 20:28 Liran Alon
  2018-01-20 20:36 ` Woodhouse, David
  0 siblings, 1 reply; 6+ messages in thread
From: Liran Alon @ 2018-01-20 20:28 UTC (permalink / raw)
  To: karahmed
  Cc: labbott, luto, Janakarajan.Natarajan, bp, torvalds,
	asit.k.mallick, rkrcmar, dave.hansen, hpa, mingo, jun.nakajima,
	x86, dwmw, ashok.raj, arjan.van.de.ven, tim.c.chen, pbonzini,
	linux-kernel, ak, peterz, tglx, gregkh, mhiramat, arjan,
	thomas.lendacky, dan.j.williams, joro, kvm, aarcange


----- karahmed@amazon.de wrote:

> From: Ashok Raj <ashok.raj@intel.com>
> 
> Add MSR passthrough for MSR_IA32_PRED_CMD and place branch predictor
> barriers on switching between VMs to avoid inter VM specte-v2
> attacks.
> 
> [peterz: rebase and changelog rewrite]
> [dwmw2: fixes]
> [karahmed: - vmx: expose PRED_CMD whenever it is available
> 	   - svm: only pass through IBPB if it is available]
> 
> Cc: Asit Mallick <asit.k.mallick@intel.com>
> Cc: Dave Hansen <dave.hansen@intel.com>
> Cc: Arjan Van De Ven <arjan.van.de.ven@intel.com>
> Cc: Tim Chen <tim.c.chen@linux.intel.com>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Andrea Arcangeli <aarcange@redhat.com>
> Cc: Andi Kleen <ak@linux.intel.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Jun Nakajima <jun.nakajima@intel.com>
> Cc: Andy Lutomirski <luto@kernel.org>
> Cc: Greg KH <gregkh@linuxfoundation.org>
> Cc: David Woodhouse <dwmw@amazon.co.uk>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Ashok Raj <ashok.raj@intel.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Link:
> https://urldefense.proofpoint.com/v2/url?u=http-3A__lkml.kernel.org_r_1515720739-2D43819-2D6-2Dgit-2Dsend-2Demail-2Dashok.raj-40intel.com&d=DwIBaQ&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=Jk6Q8nNzkQ6LJ6g42qARkg6ryIDGQr-yKXPNGZbpTx0&m=0Y6G18aD_Uxu0jx8J4AbITM-rlF_AyH591Zg5HwA5L8&s=uf8SxTOp8zu-Q5H9l-Ko-UoLUgvfuN5bvLdJwe6kUXc&e=
> 
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
> ---
>  arch/x86/kvm/svm.c | 14 ++++++++++++++
>  arch/x86/kvm/vmx.c |  4 ++++
>  2 files changed, 18 insertions(+)
> 
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 2744b973..cfdb9ab 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -529,6 +529,7 @@ struct svm_cpu_data {
>  	struct kvm_ldttss_desc *tss_desc;
>  
>  	struct page *save_area;
> +	struct vmcb *current_vmcb;
>  };
>  
>  static DEFINE_PER_CPU(struct svm_cpu_data *, svm_data);
> @@ -918,6 +919,9 @@ static void svm_vcpu_init_msrpm(u32 *msrpm)
>  
>  		set_msr_interception(msrpm, direct_access_msrs[i].index, 1, 1);
>  	}
> +
> +	if (boot_cpu_has(X86_FEATURE_AMD_PRED_CMD))
> +		set_msr_interception(msrpm, MSR_IA32_PRED_CMD, 1, 1);
>  }
>  
>  static void add_msr_offset(u32 offset)
> @@ -1706,11 +1710,17 @@ static void svm_free_vcpu(struct kvm_vcpu
> *vcpu)
>  	__free_pages(virt_to_page(svm->nested.msrpm), MSRPM_ALLOC_ORDER);
>  	kvm_vcpu_uninit(vcpu);
>  	kmem_cache_free(kvm_vcpu_cache, svm);
> +	/*
> +	 * The vmcb page can be recycled, causing a false negative in
> +	 * svm_vcpu_load(). So do a full IBPB now.
> +	 */
> +	indirect_branch_prediction_barrier();
>  }
>  
>  static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
>  {
>  	struct vcpu_svm *svm = to_svm(vcpu);
> +	struct svm_cpu_data *sd = per_cpu(svm_data, cpu);
>  	int i;
>  
>  	if (unlikely(cpu != vcpu->cpu)) {
> @@ -1739,6 +1749,10 @@ static void svm_vcpu_load(struct kvm_vcpu
> *vcpu, int cpu)
>  	if (static_cpu_has(X86_FEATURE_RDTSCP))
>  		wrmsrl(MSR_TSC_AUX, svm->tsc_aux);
>  
> +	if (sd->current_vmcb != svm->vmcb) {
> +		sd->current_vmcb = svm->vmcb;
> +		indirect_branch_prediction_barrier();
> +	}
>  	avic_vcpu_load(vcpu, cpu);
>  }
>  
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index d1e25db..3b64de2 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -2279,6 +2279,7 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu,
> int cpu)
>  	if (per_cpu(current_vmcs, cpu) != vmx->loaded_vmcs->vmcs) {
>  		per_cpu(current_vmcs, cpu) = vmx->loaded_vmcs->vmcs;
>  		vmcs_load(vmx->loaded_vmcs->vmcs);
> +		indirect_branch_prediction_barrier();
>  	}
>  
>  	if (!already_loaded) {
> @@ -6791,6 +6792,9 @@ static __init int hardware_setup(void)
>  		kvm_tsc_scaling_ratio_frac_bits = 48;
>  	}
>  
> +	if (boot_cpu_has(X86_FEATURE_SPEC_CTRL))
> +		vmx_disable_intercept_for_msr(MSR_IA32_PRED_CMD, false);
> +
>  	vmx_disable_intercept_for_msr(MSR_FS_BASE, false);
>  	vmx_disable_intercept_for_msr(MSR_GS_BASE, false);
>  	vmx_disable_intercept_for_msr(MSR_KERNEL_GS_BASE, true);
> -- 
> 2.7.4

Isn't it cleaner to check for "boot_cpu_has(X86_FEATURE_IBPB)" both in svm_vcpu_init_msrpm() and hardware_setup()?

-Liran

^ permalink raw reply	[flat|nested] 6+ messages in thread
* [RFC 00/10] Speculation Control feature support
@ 2018-01-20 19:22 KarimAllah Ahmed
  2018-01-20 19:22 ` [RFC 02/10] x86/kvm: Add IBPB support KarimAllah Ahmed
  0 siblings, 1 reply; 6+ messages in thread
From: KarimAllah Ahmed @ 2018-01-20 19:22 UTC (permalink / raw)
  To: linux-kernel
  Cc: KarimAllah Ahmed, Andi Kleen, Andrea Arcangeli, Andy Lutomirski,
	Arjan van de Ven, Ashok Raj, Asit Mallick, Borislav Petkov,
	Dan Williams, Dave Hansen, David Woodhouse, Greg Kroah-Hartman,
	H . Peter Anvin, Ingo Molnar, Janakarajan Natarajan, Joerg Roedel,
	Jun Nakajima, Laura Abbott, Linus Torvalds,
	Masami Hiramatsu <m

Start using the newly-added microcode features for speculation control on both
Intel and AMD CPUs to protect against Spectre v2.

This patch series covers interrupts, system calls, context switching between
processes, and context switching between VMs. It also exposes Indirect Branch
Prediction Barrier MSR, aka IBPB MSR, to KVM guests.

TODO:

- Introduce a microcode blacklist to disable the feature for broken microcodes.
- Restrict/Unrestrict the speculation (by toggling IBRS) around VMExit and
  VMEnter for KVM and expose IBRS to guests.

Ashok Raj (1):
  x86/kvm: Add IBPB support

David Woodhouse (1):
  x86/speculation: Add basic IBRS support infrastructure

KarimAllah Ahmed (1):
  x86: Simplify spectre_v2 command line parsing

Thomas Gleixner (4):
  x86/speculation: Add basic support for IBPB
  x86/speculation: Use Indirect Branch Prediction Barrier in context
    switch
  x86/speculation: Add inlines to control Indirect Branch Speculation
  x86/idle: Control Indirect Branch Speculation in idle

Tim Chen (3):
  x86/mm: Only flush indirect branches when switching into non dumpable
    process
  x86/enter: Create macros to restrict/unrestrict Indirect Branch
    Speculation
  x86/enter: Use IBRS on syscall and interrupts

 Documentation/admin-guide/kernel-parameters.txt |   1 +
 arch/x86/entry/calling.h                        |  73 ++++++++++
 arch/x86/entry/entry_64.S                       |  35 ++++-
 arch/x86/entry/entry_64_compat.S                |  21 ++-
 arch/x86/include/asm/cpufeatures.h              |   2 +
 arch/x86/include/asm/mwait.h                    |  14 ++
 arch/x86/include/asm/nospec-branch.h            |  54 ++++++-
 arch/x86/kernel/cpu/bugs.c                      | 183 +++++++++++++++---------
 arch/x86/kernel/process.c                       |  14 ++
 arch/x86/kvm/svm.c                              |  14 ++
 arch/x86/kvm/vmx.c                              |   4 +
 arch/x86/mm/tlb.c                               |  21 ++-
 12 files changed, 359 insertions(+), 77 deletions(-)


Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Asit Mallick <asit.k.mallick@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jun Nakajima <jun.nakajima@intel.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: x86@kernel.org

-- 
2.7.4

^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2018-01-22 19:31 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2018-01-20 20:28 [RFC 02/10] x86/kvm: Add IBPB support Liran Alon
2018-01-20 20:36 ` Woodhouse, David
  -- strict thread matches above, loose matches on Subject: below --
2018-01-20 19:22 [RFC 00/10] Speculation Control feature support KarimAllah Ahmed
2018-01-20 19:22 ` [RFC 02/10] x86/kvm: Add IBPB support KarimAllah Ahmed
2018-01-20 20:18   ` Woodhouse, David
2018-01-22 18:56   ` Jim Mattson
2018-01-22 19:31     ` Jim Mattson

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