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backport: KVM: x86: Emulate MSR_IA32_ARCH_CAPABILITIES on AMD hosts

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backport this and supporting patches to ensure Ryzen/Epyc CPUs work
with QEMU and it's new MDS mitigation helpers, which also base on
MSRs

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
This commit is contained in:
Thomas Lamprecht 2019-06-13 20:54:14 +02:00
parent c523771b01
commit 045bc2ba9d
3 changed files with 353 additions and 0 deletions
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180
patches/kernel/0010-KVM-Take-vcpu-mutex-outside-vcpu_load.patch Normal file
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@ -0,0 +1,180 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Christoffer Dall <christoffer.dall@linaro.org>
Date: Mon, 4 Dec 2017 21:35:23 +0100
Subject: [PATCH] KVM: Take vcpu->mutex outside vcpu_load
As we're about to call vcpu_load() from architecture-specific
implementations of the KVM vcpu ioctls, but yet we access data
structures protected by the vcpu->mutex in the generic code, factor
this logic out from vcpu_load().
x86 is the only architecture which calls vcpu_load() outside of the main
vcpu ioctl function, and these calls will no longer take the vcpu mutex
following this patch. However, with the exception of
kvm_arch_vcpu_postcreate (see below), the callers are either in the
creation or destruction path of the VCPU, which means there cannot be
any concurrent access to the data structure, because the file descriptor
is not yet accessible, or is already gone.
kvm_arch_vcpu_postcreate makes the newly created vcpu potentially
accessible by other in-kernel threads through the kvm->vcpus array, and
we therefore take the vcpu mutex in this case directly.
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit ec7660ccdd2b71d8c7f0243f8590253713e9b75d)
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
arch/x86/kvm/vmx.c | 4 +---
arch/x86/kvm/x86.c | 20 +++++++-------------
include/linux/kvm_host.h | 2 +-
virt/kvm/kvm_main.c | 17 ++++++-----------
4 files changed, 15 insertions(+), 28 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index bf348fee4bd5..38e50b40db5a 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -9959,10 +9959,8 @@ static void vmx_switch_vmcs(struct kvm_vcpu *vcpu, struct loaded_vmcs *vmcs)
static void vmx_free_vcpu_nested(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
- int r;
- r = vcpu_load(vcpu);
- BUG_ON(r);
+ vcpu_load(vcpu);
vmx_switch_vmcs(vcpu, &vmx->vmcs01);
free_nested(vmx);
vcpu_put(vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ac17f53812af..c578a90f1128 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7949,16 +7949,12 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm,
int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
{
- int r;
-
kvm_vcpu_mtrr_init(vcpu);
- r = vcpu_load(vcpu);
- if (r)
- return r;
+ vcpu_load(vcpu);
kvm_vcpu_reset(vcpu, false);
kvm_mmu_setup(vcpu);
vcpu_put(vcpu);
- return r;
+ return 0;
}
void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
@@ -7968,13 +7964,15 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
kvm_hv_vcpu_postcreate(vcpu);
- if (vcpu_load(vcpu))
+ if (mutex_lock_killable(&vcpu->mutex))
return;
+ vcpu_load(vcpu);
msr.data = 0x0;
msr.index = MSR_IA32_TSC;
msr.host_initiated = true;
kvm_write_tsc(vcpu, &msr);
vcpu_put(vcpu);
+ mutex_unlock(&vcpu->mutex);
if (!kvmclock_periodic_sync)
return;
@@ -7985,11 +7983,9 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
{
- int r;
vcpu->arch.apf.msr_val = 0;
- r = vcpu_load(vcpu);
- BUG_ON(r);
+ vcpu_load(vcpu);
kvm_mmu_unload(vcpu);
vcpu_put(vcpu);
@@ -8363,9 +8359,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
static void kvm_unload_vcpu_mmu(struct kvm_vcpu *vcpu)
{
- int r;
- r = vcpu_load(vcpu);
- BUG_ON(r);
+ vcpu_load(vcpu);
kvm_mmu_unload(vcpu);
vcpu_put(vcpu);
}
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c807eab9c1d3..6684da3f197f 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -533,7 +533,7 @@ static inline int kvm_vcpu_get_idx(struct kvm_vcpu *vcpu)
int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id);
void kvm_vcpu_uninit(struct kvm_vcpu *vcpu);
-int __must_check vcpu_load(struct kvm_vcpu *vcpu);
+void vcpu_load(struct kvm_vcpu *vcpu);
void vcpu_put(struct kvm_vcpu *vcpu);
#ifdef __KVM_HAVE_IOAPIC
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 238ddbc127e1..0d2eddfdf785 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -151,17 +151,12 @@ bool kvm_is_reserved_pfn(kvm_pfn_t pfn)
/*
* Switches to specified vcpu, until a matching vcpu_put()
*/
-int vcpu_load(struct kvm_vcpu *vcpu)
+void vcpu_load(struct kvm_vcpu *vcpu)
{
- int cpu;
-
- if (mutex_lock_killable(&vcpu->mutex))
- return -EINTR;
- cpu = get_cpu();
+ int cpu = get_cpu();
preempt_notifier_register(&vcpu->preempt_notifier);
kvm_arch_vcpu_load(vcpu, cpu);
put_cpu();
- return 0;
}
EXPORT_SYMBOL_GPL(vcpu_load);
@@ -171,7 +166,6 @@ void vcpu_put(struct kvm_vcpu *vcpu)
kvm_arch_vcpu_put(vcpu);
preempt_notifier_unregister(&vcpu->preempt_notifier);
preempt_enable();
- mutex_unlock(&vcpu->mutex);
}
EXPORT_SYMBOL_GPL(vcpu_put);
@@ -2562,9 +2556,9 @@ static long kvm_vcpu_ioctl(struct file *filp,
#endif
- r = vcpu_load(vcpu);
- if (r)
- return r;
+ if (mutex_lock_killable(&vcpu->mutex))
+ return -EINTR;
+ vcpu_load(vcpu);
switch (ioctl) {
case KVM_RUN: {
struct pid *oldpid;
@@ -2737,6 +2731,7 @@ static long kvm_vcpu_ioctl(struct file *filp,
}
out:
vcpu_put(vcpu);
+ mutex_unlock(&vcpu->mutex);
kfree(fpu);
kfree(kvm_sregs);
return r;

40
patches/kernel/0011-kvm-x86-Don-t-modify-MSR_PLATFORM_INFO-on-vCPU-reset.patch Normal file
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@ -0,0 +1,40 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jim Mattson <jmattson@google.com>
Date: Tue, 30 Oct 2018 12:20:21 -0700
Subject: [PATCH] kvm: x86: Don't modify MSR_PLATFORM_INFO on vCPU reset
If userspace has provided a different value for this MSR (e.g with the
turbo bits set), the userspace-provided value should survive a vCPU
reset. For backwards compatibility, MSR_PLATFORM_INFO is initialized
in kvm_arch_vcpu_setup.
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Drew Schmitt <dasch@google.com>
Cc: Abhiroop Dabral <adabral@paloaltonetworks.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit e53d88af63ab4104e1226b8f9959f1e9903da10b)
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
arch/x86/kvm/x86.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c578a90f1128..e1f16d02e44f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7949,6 +7949,7 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm,
int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
{
+ vcpu->arch.msr_platform_info = MSR_PLATFORM_INFO_CPUID_FAULT;
kvm_vcpu_mtrr_init(vcpu);
vcpu_load(vcpu);
kvm_vcpu_reset(vcpu, false);
@@ -8050,7 +8051,6 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
kvm_pmu_reset(vcpu);
vcpu->arch.smbase = 0x30000;
- vcpu->arch.msr_platform_info = MSR_PLATFORM_INFO_CPUID_FAULT;
vcpu->arch.msr_misc_features_enables = 0;
vcpu->arch.xcr0 = XFEATURE_MASK_FP;

133
patches/kernel/0012-KVM-x86-Emulate-MSR_IA32_ARCH_CAPABILITIES-on-AMD-ho.patch Normal file
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@ -0,0 +1,133 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <sean.j.christopherson@intel.com>
Date: Thu, 7 Mar 2019 15:43:02 -0800
Subject: [PATCH] KVM: x86: Emulate MSR_IA32_ARCH_CAPABILITIES on AMD hosts
BugLink: https://bugs.launchpad.net/bugs/1823060
commit 0cf9135b773bf32fba9dd8e6699c1b331ee4b749 upstream.
The CPUID flag ARCH_CAPABILITIES is unconditioinally exposed to host
userspace for all x86 hosts, i.e. KVM advertises ARCH_CAPABILITIES
regardless of hardware support under the pretense that KVM fully
emulates MSR_IA32_ARCH_CAPABILITIES. Unfortunately, only VMX hosts
handle accesses to MSR_IA32_ARCH_CAPABILITIES (despite KVM_GET_MSRS
also reporting MSR_IA32_ARCH_CAPABILITIES for all hosts).
Move the MSR_IA32_ARCH_CAPABILITIES handling to common x86 code so
that it's emulated on AMD hosts.
Fixes: 1eaafe91a0df4 ("kvm: x86: IA32_ARCH_CAPABILITIES is always supported")
Cc: stable@vger.kernel.org
Reported-by: Xiaoyao Li <xiaoyao.li@linux.intel.com>
Cc: Jim Mattson <jmattson@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
(back ported from commit 0cf9135b773bf32fba9dd8e6699c1b331ee4b749)
Backported-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/vmx.c | 14 --------------
arch/x86/kvm/x86.c | 12 ++++++++++++
3 files changed, 13 insertions(+), 14 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index e76012ca0ddc..fa57f78dff2d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -508,6 +508,7 @@ struct kvm_vcpu_arch {
bool tpr_access_reporting;
u64 ia32_xss;
u64 microcode_version;
+ u64 arch_capabilities;
/*
* Paging state of the vcpu
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 38e50b40db5a..1911ec5e26c1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -750,7 +750,6 @@ struct vcpu_vmx {
u64 msr_guest_kernel_gs_base;
#endif
- u64 arch_capabilities;
u64 spec_ctrl;
u32 vm_entry_controls_shadow;
@@ -3477,12 +3476,6 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
msr_info->data = to_vmx(vcpu)->spec_ctrl;
break;
- case MSR_IA32_ARCH_CAPABILITIES:
- if (!msr_info->host_initiated &&
- !guest_cpuid_has(vcpu, X86_FEATURE_ARCH_CAPABILITIES))
- return 1;
- msr_info->data = to_vmx(vcpu)->arch_capabilities;
- break;
case MSR_IA32_SYSENTER_CS:
msr_info->data = vmcs_read32(GUEST_SYSENTER_CS);
break;
@@ -3644,11 +3637,6 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
vmx_disable_intercept_for_msr(vmx->vmcs01.msr_bitmap, MSR_IA32_PRED_CMD,
MSR_TYPE_W);
break;
- case MSR_IA32_ARCH_CAPABILITIES:
- if (!msr_info->host_initiated)
- return 1;
- vmx->arch_capabilities = data;
- break;
case MSR_IA32_CR_PAT:
if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) {
if (!kvm_mtrr_valid(vcpu, MSR_IA32_CR_PAT, data))
@@ -5906,8 +5894,6 @@ static void vmx_vcpu_setup(struct vcpu_vmx *vmx)
++vmx->nmsrs;
}
- vmx->arch_capabilities = kvm_get_arch_capabilities();
-
vm_exit_controls_init(vmx, vmcs_config.vmexit_ctrl);
/* 22.2.1, 20.8.1 */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e1f16d02e44f..bf76e7cd9837 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2246,6 +2246,11 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
if (msr_info->host_initiated)
vcpu->arch.microcode_version = data;
break;
+ case MSR_IA32_ARCH_CAPABILITIES:
+ if (!msr_info->host_initiated)
+ return 1;
+ vcpu->arch.arch_capabilities = data;
+ break;
case MSR_EFER:
return set_efer(vcpu, data);
case MSR_K7_HWCR:
@@ -2541,6 +2546,12 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
case MSR_IA32_UCODE_REV:
msr_info->data = vcpu->arch.microcode_version;
break;
+ case MSR_IA32_ARCH_CAPABILITIES:
+ if (!msr_info->host_initiated &&
+ !guest_cpuid_has(vcpu, X86_FEATURE_ARCH_CAPABILITIES))
+ return 1;
+ msr_info->data = vcpu->arch.arch_capabilities;
+ break;
case MSR_IA32_TSC:
msr_info->data = kvm_scale_tsc(vcpu, rdtsc()) + vcpu->arch.tsc_offset;
break;
@@ -7949,6 +7960,7 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm,
int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
{
+ vcpu->arch.arch_capabilities = kvm_get_arch_capabilities();
vcpu->arch.msr_platform_info = MSR_PLATFORM_INFO_CPUID_FAULT;
kvm_vcpu_mtrr_init(vcpu);
vcpu_load(vcpu);