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* [PATCH v2 0/3] KVM: x86: fixes for speculation bug feature reporting
@ 2019-08-21  8:26 Paolo Bonzini
  2019-08-21  8:26 ` [PATCH 1/3] KVM: x86: fix reporting of AMD speculation bug CPUID leaf Paolo Bonzini
                   ` (2 more replies)
  0 siblings, 3 replies; 14+ messages in thread
From: Paolo Bonzini @ 2019-08-21  8:26 UTC (permalink / raw)
  To: linux-kernel, kvm; +Cc: jmattson, ehabkost, konrad.wilk

Patches 1 and 2 are the same as the previous patch, but using
svm_get_supported_cpuid and with a fix to the placement of cpuid_mask.

Patch 3 is new and, unlike the previous one, will only be in kvm/next.

Paolo Bonzini (3):
  KVM: x86: fix reporting of AMD speculation bug CPUID leaf
  KVM: x86: always expose VIRT_SSBD to guests
  KVM: x86: use Intel speculation bugs and features as derived in
    generic x86 code

 arch/x86/kvm/cpuid.c | 27 +++++++++++++++++++--------
 arch/x86/kvm/svm.c   | 13 +++++++++----
 arch/x86/kvm/x86.c   |  7 +++++++
 3 files changed, 35 insertions(+), 12 deletions(-)

-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 14+ messages in thread

* [PATCH 1/3] KVM: x86: fix reporting of AMD speculation bug CPUID leaf
  2019-08-21  8:26 [PATCH v2 0/3] KVM: x86: fixes for speculation bug feature reporting Paolo Bonzini
@ 2019-08-21  8:26 ` Paolo Bonzini
  2019-08-21 19:45   ` Jim Mattson
                     ` (2 more replies)
  2019-08-21  8:26 ` [PATCH 2/3] KVM: x86: always expose VIRT_SSBD to guests Paolo Bonzini
  2019-08-21  8:26 ` [PATCH 3/3] KVM: x86: use Intel speculation bugs and features as derived in generic x86 code Paolo Bonzini
  2 siblings, 3 replies; 14+ messages in thread
From: Paolo Bonzini @ 2019-08-21  8:26 UTC (permalink / raw)
  To: linux-kernel, kvm; +Cc: jmattson, ehabkost, konrad.wilk

The AMD_* bits have to be set from the vendor-independent
feature and bug flags, because KVM_GET_SUPPORTED_CPUID does not care
about the vendor and they should be set on Intel processors as well.
On top of this, SSBD, STIBP and AMD_SSB_NO bit were not set, and
VIRT_SSBD does not have to be added manually because it is a
cpufeature that comes directly from the host's CPUID bit.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/cpuid.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 22c2720cd948..43caeb6059b9 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -729,18 +729,23 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
 			g_phys_as = phys_as;
 		entry->eax = g_phys_as | (virt_as << 8);
 		entry->edx = 0;
+		entry->ebx &= kvm_cpuid_8000_0008_ebx_x86_features;
+		cpuid_mask(&entry->ebx, CPUID_8000_0008_EBX);
 		/*
-		 * IBRS, IBPB and VIRT_SSBD aren't necessarily present in
-		 * hardware cpuid
+		 * AMD has separate bits for each SPEC_CTRL bit.
+		 * arch/x86/kernel/cpu/bugs.c is kind enough to
+		 * record that in cpufeatures so use them.
 		 */
-		if (boot_cpu_has(X86_FEATURE_AMD_IBPB))
+		if (boot_cpu_has(X86_FEATURE_IBPB))
 			entry->ebx |= F(AMD_IBPB);
-		if (boot_cpu_has(X86_FEATURE_AMD_IBRS))
+		if (boot_cpu_has(X86_FEATURE_IBRS))
 			entry->ebx |= F(AMD_IBRS);
-		if (boot_cpu_has(X86_FEATURE_VIRT_SSBD))
-			entry->ebx |= F(VIRT_SSBD);
-		entry->ebx &= kvm_cpuid_8000_0008_ebx_x86_features;
-		cpuid_mask(&entry->ebx, CPUID_8000_0008_EBX);
+		if (boot_cpu_has(X86_FEATURE_STIBP))
+			entry->ebx |= F(AMD_STIBP);
+		if (boot_cpu_has(X86_FEATURE_SSBD))
+			entry->ebx |= F(AMD_SSBD);
+		if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
+			entry->ebx |= F(AMD_SSB_NO);
 		/*
 		 * The preference is to use SPEC CTRL MSR instead of the
 		 * VIRT_SPEC MSR.
-- 
1.8.3.1



^ permalink raw reply	[flat|nested] 14+ messages in thread

* [PATCH 2/3] KVM: x86: always expose VIRT_SSBD to guests
  2019-08-21  8:26 [PATCH v2 0/3] KVM: x86: fixes for speculation bug feature reporting Paolo Bonzini
  2019-08-21  8:26 ` [PATCH 1/3] KVM: x86: fix reporting of AMD speculation bug CPUID leaf Paolo Bonzini
@ 2019-08-21  8:26 ` Paolo Bonzini
  2019-08-21 19:47   ` Jim Mattson
                     ` (2 more replies)
  2019-08-21  8:26 ` [PATCH 3/3] KVM: x86: use Intel speculation bugs and features as derived in generic x86 code Paolo Bonzini
  2 siblings, 3 replies; 14+ messages in thread
From: Paolo Bonzini @ 2019-08-21  8:26 UTC (permalink / raw)
  To: linux-kernel, kvm; +Cc: jmattson, ehabkost, konrad.wilk

Even though it is preferrable to use SPEC_CTRL (represented by
X86_FEATURE_AMD_SSBD) instead of VIRT_SPEC, VIRT_SPEC is always
supported anyway because otherwise it would be impossible to
migrate from old to new CPUs.  Make this apparent in the
result of KVM_GET_SUPPORTED_CPUID as well.

While at it, reuse X86_FEATURE_* constants for the SVM leaf too.

However, we need to hide the bit on Intel processors, so move
the setting to svm_set_supported_cpuid.

Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reported-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/svm.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index e3d3b2128f2b..c5120a9519f3 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -68,10 +68,8 @@
 #define SEG_TYPE_LDT 2
 #define SEG_TYPE_BUSY_TSS16 3
 
-#define SVM_FEATURE_NPT            (1 <<  0)
 #define SVM_FEATURE_LBRV           (1 <<  1)
 #define SVM_FEATURE_SVML           (1 <<  2)
-#define SVM_FEATURE_NRIP           (1 <<  3)
 #define SVM_FEATURE_TSC_RATE       (1 <<  4)
 #define SVM_FEATURE_VMCB_CLEAN     (1 <<  5)
 #define SVM_FEATURE_FLUSH_ASID     (1 <<  6)
@@ -5933,6 +5931,8 @@ static void svm_cpuid_update(struct kvm_vcpu *vcpu)
 	guest_cpuid_clear(vcpu, X86_FEATURE_X2APIC);
 }
 
+#define F(x) bit(X86_FEATURE_##x)
+
 static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
 {
 	switch (func) {
@@ -5944,6 +5944,11 @@ static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
 		if (nested)
 			entry->ecx |= (1 << 2); /* Set SVM bit */
 		break;
+	case 0x80000008:
+		if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) ||
+		     boot_cpu_has(X86_FEATURE_AMD_SSBD))
+			entry->ebx |= F(VIRT_SSBD);
+		break;
 	case 0x8000000A:
 		entry->eax = 1; /* SVM revision 1 */
 		entry->ebx = 8; /* Lets support 8 ASIDs in case we add proper
@@ -5954,11 +5959,11 @@ static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
 
 		/* Support next_rip if host supports it */
 		if (boot_cpu_has(X86_FEATURE_NRIPS))
-			entry->edx |= SVM_FEATURE_NRIP;
+			entry->edx |= F(NRIPS);
 
 		/* Support NPT for the guest if enabled */
 		if (npt_enabled)
-			entry->edx |= SVM_FEATURE_NPT;
+			entry->edx |= F(NPT);
 
 		break;
 	case 0x8000001F:
-- 
1.8.3.1



^ permalink raw reply	[flat|nested] 14+ messages in thread

* [PATCH 3/3] KVM: x86: use Intel speculation bugs and features as derived in generic x86 code
  2019-08-21  8:26 [PATCH v2 0/3] KVM: x86: fixes for speculation bug feature reporting Paolo Bonzini
  2019-08-21  8:26 ` [PATCH 1/3] KVM: x86: fix reporting of AMD speculation bug CPUID leaf Paolo Bonzini
  2019-08-21  8:26 ` [PATCH 2/3] KVM: x86: always expose VIRT_SSBD to guests Paolo Bonzini
@ 2019-08-21  8:26 ` Paolo Bonzini
  2019-08-21 19:48   ` Jim Mattson
  2019-08-22 18:45   ` Konrad Rzeszutek Wilk
  2 siblings, 2 replies; 14+ messages in thread
From: Paolo Bonzini @ 2019-08-21  8:26 UTC (permalink / raw)
  To: linux-kernel, kvm; +Cc: jmattson, ehabkost, konrad.wilk

Similar to AMD bits, set the Intel bits from the vendor-independent
feature and bug flags, because KVM_GET_SUPPORTED_CPUID does not care
about the vendor and they should be set on AMD processors as well.

Suggested-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/cpuid.c | 6 ++++++
 arch/x86/kvm/x86.c   | 7 +++++++
 2 files changed, 13 insertions(+)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 43caeb6059b9..dd5985eb61b4 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -392,6 +392,12 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry, int index)
 
 		entry->edx &= kvm_cpuid_7_0_edx_x86_features;
 		cpuid_mask(&entry->edx, CPUID_7_EDX);
+		if (boot_cpu_has(X86_FEATURE_IBPB) && boot_cpu_has(X86_FEATURE_IBRS))
+			entry->edx |= F(SPEC_CTRL);
+		if (boot_cpu_has(X86_FEATURE_STIBP))
+			entry->edx |= F(INTEL_STIBP);
+		if (boot_cpu_has(X86_FEATURE_SSBD))
+			entry->edx |= F(SPEC_CTRL_SSBD);
 		/*
 		 * We emulate ARCH_CAPABILITIES in software even
 		 * if the host doesn't support it.
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 93b0bd45ac73..6b81c7609d09 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1254,6 +1254,13 @@ static u64 kvm_get_arch_capabilities(void)
 	if (l1tf_vmx_mitigation != VMENTER_L1D_FLUSH_NEVER)
 		data |= ARCH_CAP_SKIP_VMENTRY_L1DFLUSH;
 
+	if (!boot_cpu_has_bug(X86_BUG_CPU_MELTDOWN))
+		data |= ARCH_CAP_RDCL_NO;
+	if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
+		data |= ARCH_CAP_SSB_NO;
+	if (!boot_cpu_has_bug(X86_BUG_MDS))
+		data |= ARCH_CAP_MDS_NO;
+
 	return data;
 }
 
-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 14+ messages in thread

* Re: [PATCH 1/3] KVM: x86: fix reporting of AMD speculation bug CPUID leaf
  2019-08-21  8:26 ` [PATCH 1/3] KVM: x86: fix reporting of AMD speculation bug CPUID leaf Paolo Bonzini
@ 2019-08-21 19:45   ` Jim Mattson
  2019-08-22 18:46   ` Konrad Rzeszutek Wilk
  2019-11-30 23:27   ` Eric Biggers
  2 siblings, 0 replies; 14+ messages in thread
From: Jim Mattson @ 2019-08-21 19:45 UTC (permalink / raw)
  To: Paolo Bonzini
  Cc: LKML, kvm list, jmattson, Eduardo Habkost, Konrad Rzeszutek Wilk

On Wed, Aug 21, 2019 at 1:27 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> The AMD_* bits have to be set from the vendor-independent
> feature and bug flags, because KVM_GET_SUPPORTED_CPUID does not care
> about the vendor and they should be set on Intel processors as well.
> On top of this, SSBD, STIBP and AMD_SSB_NO bit were not set, and
> VIRT_SSBD does not have to be added manually because it is a
> cpufeature that comes directly from the host's CPUID bit.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Jim Mattson <jmattson@google.com>

^ permalink raw reply	[flat|nested] 14+ messages in thread

* Re: [PATCH 2/3] KVM: x86: always expose VIRT_SSBD to guests
  2019-08-21  8:26 ` [PATCH 2/3] KVM: x86: always expose VIRT_SSBD to guests Paolo Bonzini
@ 2019-08-21 19:47   ` Jim Mattson
  2019-08-22 18:44   ` Konrad Rzeszutek Wilk
  2019-10-01 22:16   ` Eduardo Habkost
  2 siblings, 0 replies; 14+ messages in thread
From: Jim Mattson @ 2019-08-21 19:47 UTC (permalink / raw)
  To: Paolo Bonzini
  Cc: LKML, kvm list, jmattson, Eduardo Habkost, Konrad Rzeszutek Wilk

On Wed, Aug 21, 2019 at 1:27 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> Even though it is preferrable to use SPEC_CTRL (represented by
> X86_FEATURE_AMD_SSBD) instead of VIRT_SPEC, VIRT_SPEC is always
> supported anyway because otherwise it would be impossible to
> migrate from old to new CPUs.  Make this apparent in the
> result of KVM_GET_SUPPORTED_CPUID as well.
>
> While at it, reuse X86_FEATURE_* constants for the SVM leaf too.
>
> However, we need to hide the bit on Intel processors, so move
> the setting to svm_set_supported_cpuid.
>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Reported-by: Eduardo Habkost <ehabkost@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Jim Mattson <jmattson@google.com>

^ permalink raw reply	[flat|nested] 14+ messages in thread

* Re: [PATCH 3/3] KVM: x86: use Intel speculation bugs and features as derived in generic x86 code
  2019-08-21  8:26 ` [PATCH 3/3] KVM: x86: use Intel speculation bugs and features as derived in generic x86 code Paolo Bonzini
@ 2019-08-21 19:48   ` Jim Mattson
  2019-08-22 18:45   ` Konrad Rzeszutek Wilk
  1 sibling, 0 replies; 14+ messages in thread
From: Jim Mattson @ 2019-08-21 19:48 UTC (permalink / raw)
  To: Paolo Bonzini
  Cc: LKML, kvm list, jmattson, Eduardo Habkost, Konrad Rzeszutek Wilk

On Wed, Aug 21, 2019 at 1:27 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> Similar to AMD bits, set the Intel bits from the vendor-independent
> feature and bug flags, because KVM_GET_SUPPORTED_CPUID does not care
> about the vendor and they should be set on AMD processors as well.
>
> Suggested-by: Jim Mattson <jmattson@google.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Jim Mattson <jmattson@google.com>

^ permalink raw reply	[flat|nested] 14+ messages in thread

* Re: [PATCH 2/3] KVM: x86: always expose VIRT_SSBD to guests
  2019-08-21  8:26 ` [PATCH 2/3] KVM: x86: always expose VIRT_SSBD to guests Paolo Bonzini
  2019-08-21 19:47   ` Jim Mattson
@ 2019-08-22 18:44   ` Konrad Rzeszutek Wilk
  2019-10-01 22:16   ` Eduardo Habkost
  2 siblings, 0 replies; 14+ messages in thread
From: Konrad Rzeszutek Wilk @ 2019-08-22 18:44 UTC (permalink / raw)
  To: Paolo Bonzini; +Cc: linux-kernel, kvm, jmattson, ehabkost

On Wed, Aug 21, 2019 at 10:26:41AM +0200, Paolo Bonzini wrote:
> Even though it is preferrable to use SPEC_CTRL (represented by
> X86_FEATURE_AMD_SSBD) instead of VIRT_SPEC, VIRT_SPEC is always
> supported anyway because otherwise it would be impossible to
> migrate from old to new CPUs.  Make this apparent in the
> result of KVM_GET_SUPPORTED_CPUID as well.
> 
> While at it, reuse X86_FEATURE_* constants for the SVM leaf too.
> 
> However, we need to hide the bit on Intel processors, so move
> the setting to svm_set_supported_cpuid.
> 
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Thank you!

^ permalink raw reply	[flat|nested] 14+ messages in thread

* Re: [PATCH 3/3] KVM: x86: use Intel speculation bugs and features as derived in generic x86 code
  2019-08-21  8:26 ` [PATCH 3/3] KVM: x86: use Intel speculation bugs and features as derived in generic x86 code Paolo Bonzini
  2019-08-21 19:48   ` Jim Mattson
@ 2019-08-22 18:45   ` Konrad Rzeszutek Wilk
  1 sibling, 0 replies; 14+ messages in thread
From: Konrad Rzeszutek Wilk @ 2019-08-22 18:45 UTC (permalink / raw)
  To: Paolo Bonzini; +Cc: linux-kernel, kvm, jmattson, ehabkost

On Wed, Aug 21, 2019 at 10:26:42AM +0200, Paolo Bonzini wrote:
> Similar to AMD bits, set the Intel bits from the vendor-independent
> feature and bug flags, because KVM_GET_SUPPORTED_CPUID does not care
> about the vendor and they should be set on AMD processors as well.
> 
> Suggested-by: Jim Mattson <jmattson@google.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Thank you!

^ permalink raw reply	[flat|nested] 14+ messages in thread

* Re: [PATCH 1/3] KVM: x86: fix reporting of AMD speculation bug CPUID leaf
  2019-08-21  8:26 ` [PATCH 1/3] KVM: x86: fix reporting of AMD speculation bug CPUID leaf Paolo Bonzini
  2019-08-21 19:45   ` Jim Mattson
@ 2019-08-22 18:46   ` Konrad Rzeszutek Wilk
  2019-11-30 23:27   ` Eric Biggers
  2 siblings, 0 replies; 14+ messages in thread
From: Konrad Rzeszutek Wilk @ 2019-08-22 18:46 UTC (permalink / raw)
  To: Paolo Bonzini; +Cc: linux-kernel, kvm, jmattson, ehabkost

On Wed, Aug 21, 2019 at 10:26:40AM +0200, Paolo Bonzini wrote:
> The AMD_* bits have to be set from the vendor-independent
> feature and bug flags, because KVM_GET_SUPPORTED_CPUID does not care
> about the vendor and they should be set on Intel processors as well.
> On top of this, SSBD, STIBP and AMD_SSB_NO bit were not set, and
> VIRT_SSBD does not have to be added manually because it is a
> cpufeature that comes directly from the host's CPUID bit.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Thank you!

^ permalink raw reply	[flat|nested] 14+ messages in thread

* Re: [PATCH 2/3] KVM: x86: always expose VIRT_SSBD to guests
  2019-08-21  8:26 ` [PATCH 2/3] KVM: x86: always expose VIRT_SSBD to guests Paolo Bonzini
  2019-08-21 19:47   ` Jim Mattson
  2019-08-22 18:44   ` Konrad Rzeszutek Wilk
@ 2019-10-01 22:16   ` Eduardo Habkost
  2019-10-06 16:08     ` Paolo Bonzini
  2 siblings, 1 reply; 14+ messages in thread
From: Eduardo Habkost @ 2019-10-01 22:16 UTC (permalink / raw)
  To: Paolo Bonzini; +Cc: linux-kernel, kvm, Jim Mattson, konrad.wilk

On Wed, Aug 21, 2019 at 10:26:41AM +0200, Paolo Bonzini wrote:
> Even though it is preferrable to use SPEC_CTRL (represented by
> X86_FEATURE_AMD_SSBD) instead of VIRT_SPEC, VIRT_SPEC is always
> supported anyway because otherwise it would be impossible to
> migrate from old to new CPUs.  Make this apparent in the
> result of KVM_GET_SUPPORTED_CPUID as well.
> 
> While at it, reuse X86_FEATURE_* constants for the SVM leaf too.
> 
> However, we need to hide the bit on Intel processors, so move
> the setting to svm_set_supported_cpuid.
> 
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Reported-by: Eduardo Habkost <ehabkost@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
[...]
> @@ -5944,6 +5944,11 @@ static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
>  		if (nested)
>  			entry->ecx |= (1 << 2); /* Set SVM bit */
>  		break;
> +	case 0x80000008:
> +		if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) ||
> +		     boot_cpu_has(X86_FEATURE_AMD_SSBD))
> +			entry->ebx |= F(VIRT_SSBD);
> +		break;

Wasn't the old code at arch/x86/kvm/cpuid.c:__do_cpuid_func()
supposed to be deleted?

               /*
                * The preference is to use SPEC CTRL MSR instead of the
                * VIRT_SPEC MSR.
                */
               if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) &&
                   !boot_cpu_has(X86_FEATURE_AMD_SSBD))
                       entry->ebx |= F(VIRT_SSBD);


-- 
Eduardo

^ permalink raw reply	[flat|nested] 14+ messages in thread

* Re: [PATCH 2/3] KVM: x86: always expose VIRT_SSBD to guests
  2019-10-01 22:16   ` Eduardo Habkost
@ 2019-10-06 16:08     ` Paolo Bonzini
  0 siblings, 0 replies; 14+ messages in thread
From: Paolo Bonzini @ 2019-10-06 16:08 UTC (permalink / raw)
  To: Eduardo Habkost; +Cc: linux-kernel, kvm, Jim Mattson, konrad.wilk

On 02/10/19 00:16, Eduardo Habkost wrote:
> Wasn't the old code at arch/x86/kvm/cpuid.c:__do_cpuid_func()
> supposed to be deleted?
> 
>                /*
>                 * The preference is to use SPEC CTRL MSR instead of the
>                 * VIRT_SPEC MSR.
>                 */
>                if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) &&
>                    !boot_cpu_has(X86_FEATURE_AMD_SSBD))
>                        entry->ebx |= F(VIRT_SSBD);

Yeah, it's harmless but also useless.

Paolo

^ permalink raw reply	[flat|nested] 14+ messages in thread

* Re: [PATCH 1/3] KVM: x86: fix reporting of AMD speculation bug CPUID leaf
  2019-08-21  8:26 ` [PATCH 1/3] KVM: x86: fix reporting of AMD speculation bug CPUID leaf Paolo Bonzini
  2019-08-21 19:45   ` Jim Mattson
  2019-08-22 18:46   ` Konrad Rzeszutek Wilk
@ 2019-11-30 23:27   ` Eric Biggers
  2019-12-09 17:55     ` Eric Biggers
  2 siblings, 1 reply; 14+ messages in thread
From: Eric Biggers @ 2019-11-30 23:27 UTC (permalink / raw)
  To: Paolo Bonzini; +Cc: linux-kernel, kvm, jmattson, ehabkost, konrad.wilk

Hi Paolo,

On Wed, Aug 21, 2019 at 10:26:40AM +0200, Paolo Bonzini wrote:
> The AMD_* bits have to be set from the vendor-independent
> feature and bug flags, because KVM_GET_SUPPORTED_CPUID does not care
> about the vendor and they should be set on Intel processors as well.
> On top of this, SSBD, STIBP and AMD_SSB_NO bit were not set, and
> VIRT_SSBD does not have to be added manually because it is a
> cpufeature that comes directly from the host's CPUID bit.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  arch/x86/kvm/cpuid.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 22c2720cd948..43caeb6059b9 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -729,18 +729,23 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
>  			g_phys_as = phys_as;
>  		entry->eax = g_phys_as | (virt_as << 8);
>  		entry->edx = 0;
> +		entry->ebx &= kvm_cpuid_8000_0008_ebx_x86_features;
> +		cpuid_mask(&entry->ebx, CPUID_8000_0008_EBX);
>  		/*
> -		 * IBRS, IBPB and VIRT_SSBD aren't necessarily present in
> -		 * hardware cpuid
> +		 * AMD has separate bits for each SPEC_CTRL bit.
> +		 * arch/x86/kernel/cpu/bugs.c is kind enough to
> +		 * record that in cpufeatures so use them.
>  		 */
> -		if (boot_cpu_has(X86_FEATURE_AMD_IBPB))
> +		if (boot_cpu_has(X86_FEATURE_IBPB))
>  			entry->ebx |= F(AMD_IBPB);
> -		if (boot_cpu_has(X86_FEATURE_AMD_IBRS))
> +		if (boot_cpu_has(X86_FEATURE_IBRS))
>  			entry->ebx |= F(AMD_IBRS);
> -		if (boot_cpu_has(X86_FEATURE_VIRT_SSBD))
> -			entry->ebx |= F(VIRT_SSBD);
> -		entry->ebx &= kvm_cpuid_8000_0008_ebx_x86_features;
> -		cpuid_mask(&entry->ebx, CPUID_8000_0008_EBX);
> +		if (boot_cpu_has(X86_FEATURE_STIBP))
> +			entry->ebx |= F(AMD_STIBP);
> +		if (boot_cpu_has(X86_FEATURE_SSBD))
> +			entry->ebx |= F(AMD_SSBD);
> +		if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
> +			entry->ebx |= F(AMD_SSB_NO);
>  		/*
>  		 * The preference is to use SPEC CTRL MSR instead of the
>  		 * VIRT_SPEC MSR.

This patch started causing a warning about an unchecked MSR access, when
starting a VM.

Processor is: "AMD Ryzen Threadripper 1950X 16-Core Processor"

The warning appears both in the host and guest kernel logs.

On the host:

	[   12.121802] unchecked MSR access error: RDMSR from 0x48 at rIP: 0xffffffff8b049765 (svm_vcpu_run+0x6a5/0x720)
	[   12.121806] Call Trace:
	[   12.121812]  ? kvm_arch_vcpu_ioctl_run+0x902/0x1b70
	[   12.121814]  ? kvm_vm_ioctl_irq_line+0x1e/0x30
	[   12.121817]  ? kvm_vcpu_ioctl+0x21e/0x560
	[   12.121821]  ? vfs_writev+0xc0/0xf0
	[   12.121824]  ? do_vfs_ioctl+0x41d/0x690
	[   12.121826]  ? ksys_ioctl+0x59/0x90
	[   12.121827]  ? __x64_sys_ioctl+0x11/0x20
	[   12.121828]  ? do_syscall_64+0x43/0x130
	[   12.121832]  ? entry_SYSCALL_64_after_hwframe+0x44/0xa9

On the guest:

	[    0.799090] unchecked MSR access error: WRMSR to 0x48 (tried to write 0x0000000000000004) at rIP: 0xffffffff81028272 (speculation_ctrl_update+0x132/0x2c0)
	[    0.801823] Call Trace:
	[    0.801831]  ? seccomp_set_mode_filter+0x18d/0x800
	[    0.801833]  speculation_ctrl_update_current+0x21/0x30
	[    0.801837]  task_update_spec_tif+0x1d/0x20
	[    0.801839]  ssb_prctl_set+0xb5/0xd0
	[    0.801841]  arch_seccomp_spec_mitigate+0x2a/0x50
	[    0.801843]  seccomp_set_mode_filter+0x788/0x800
	[    0.801845]  do_seccomp+0x34/0x200
	[    0.801849]  __x64_sys_seccomp+0x15/0x20
	[    0.801852]  do_syscall_64+0x4a/0x1f0
	[    0.809349]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
	[    0.810548] RIP: 0033:0x7f431db92e9d
	[    0.811528] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d b3 5f 0c 00 f7 d8 64 89 01 48
	[    0.814754] RSP: 002b:00007ffca5506788 EFLAGS: 00000246 ORIG_RAX: 000000000000013d
	[    0.816075] RAX: ffffffffffffffda RBX: 0000556956c07580 RCX: 00007f431db92e9d
	[    0.817367] RDX: 0000556956c023e0 RSI: 0000000000000000 RDI: 0000000000000001
	[    0.818698] RBP: 0000556956c023e0 R08: 0000000000000007 R09: 0000556956b73730
	[    0.819948] R10: 0000556956b7101a R11: 0000000000000246 R12: 000000000000002d
	[    0.821184] R13: 0040000000002001 R14: 00007f431d9b4898 R15: 0000000000000000

The VM still boots though.

I've actually been seeing this for a while but haven't had a chance to bisect it
until now.

Reverting the commit (4c6903a0f9d76) on mainline makes the warnings go away.

Any ideas?  Presumably something isn't working as intended.

- Eric

^ permalink raw reply	[flat|nested] 14+ messages in thread

* Re: [PATCH 1/3] KVM: x86: fix reporting of AMD speculation bug CPUID leaf
  2019-11-30 23:27   ` Eric Biggers
@ 2019-12-09 17:55     ` Eric Biggers
  0 siblings, 0 replies; 14+ messages in thread
From: Eric Biggers @ 2019-12-09 17:55 UTC (permalink / raw)
  To: Paolo Bonzini; +Cc: linux-kernel, kvm, jmattson, ehabkost, konrad.wilk

On Sat, Nov 30, 2019 at 03:27:33PM -0800, Eric Biggers wrote:
> Hi Paolo,
> 
> On Wed, Aug 21, 2019 at 10:26:40AM +0200, Paolo Bonzini wrote:
> > The AMD_* bits have to be set from the vendor-independent
> > feature and bug flags, because KVM_GET_SUPPORTED_CPUID does not care
> > about the vendor and they should be set on Intel processors as well.
> > On top of this, SSBD, STIBP and AMD_SSB_NO bit were not set, and
> > VIRT_SSBD does not have to be added manually because it is a
> > cpufeature that comes directly from the host's CPUID bit.
> > 
> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> > ---
> >  arch/x86/kvm/cpuid.c | 21 +++++++++++++--------
> >  1 file changed, 13 insertions(+), 8 deletions(-)
> > 
> > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> > index 22c2720cd948..43caeb6059b9 100644
> > --- a/arch/x86/kvm/cpuid.c
> > +++ b/arch/x86/kvm/cpuid.c
> > @@ -729,18 +729,23 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
> >  			g_phys_as = phys_as;
> >  		entry->eax = g_phys_as | (virt_as << 8);
> >  		entry->edx = 0;
> > +		entry->ebx &= kvm_cpuid_8000_0008_ebx_x86_features;
> > +		cpuid_mask(&entry->ebx, CPUID_8000_0008_EBX);
> >  		/*
> > -		 * IBRS, IBPB and VIRT_SSBD aren't necessarily present in
> > -		 * hardware cpuid
> > +		 * AMD has separate bits for each SPEC_CTRL bit.
> > +		 * arch/x86/kernel/cpu/bugs.c is kind enough to
> > +		 * record that in cpufeatures so use them.
> >  		 */
> > -		if (boot_cpu_has(X86_FEATURE_AMD_IBPB))
> > +		if (boot_cpu_has(X86_FEATURE_IBPB))
> >  			entry->ebx |= F(AMD_IBPB);
> > -		if (boot_cpu_has(X86_FEATURE_AMD_IBRS))
> > +		if (boot_cpu_has(X86_FEATURE_IBRS))
> >  			entry->ebx |= F(AMD_IBRS);
> > -		if (boot_cpu_has(X86_FEATURE_VIRT_SSBD))
> > -			entry->ebx |= F(VIRT_SSBD);
> > -		entry->ebx &= kvm_cpuid_8000_0008_ebx_x86_features;
> > -		cpuid_mask(&entry->ebx, CPUID_8000_0008_EBX);
> > +		if (boot_cpu_has(X86_FEATURE_STIBP))
> > +			entry->ebx |= F(AMD_STIBP);
> > +		if (boot_cpu_has(X86_FEATURE_SSBD))
> > +			entry->ebx |= F(AMD_SSBD);
> > +		if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
> > +			entry->ebx |= F(AMD_SSB_NO);
> >  		/*
> >  		 * The preference is to use SPEC CTRL MSR instead of the
> >  		 * VIRT_SPEC MSR.
> 
> This patch started causing a warning about an unchecked MSR access, when
> starting a VM.
> 
> Processor is: "AMD Ryzen Threadripper 1950X 16-Core Processor"
> 
> The warning appears both in the host and guest kernel logs.
> 
> On the host:
> 
> 	[   12.121802] unchecked MSR access error: RDMSR from 0x48 at rIP: 0xffffffff8b049765 (svm_vcpu_run+0x6a5/0x720)
> 	[   12.121806] Call Trace:
> 	[   12.121812]  ? kvm_arch_vcpu_ioctl_run+0x902/0x1b70
> 	[   12.121814]  ? kvm_vm_ioctl_irq_line+0x1e/0x30
> 	[   12.121817]  ? kvm_vcpu_ioctl+0x21e/0x560
> 	[   12.121821]  ? vfs_writev+0xc0/0xf0
> 	[   12.121824]  ? do_vfs_ioctl+0x41d/0x690
> 	[   12.121826]  ? ksys_ioctl+0x59/0x90
> 	[   12.121827]  ? __x64_sys_ioctl+0x11/0x20
> 	[   12.121828]  ? do_syscall_64+0x43/0x130
> 	[   12.121832]  ? entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> On the guest:
> 
> 	[    0.799090] unchecked MSR access error: WRMSR to 0x48 (tried to write 0x0000000000000004) at rIP: 0xffffffff81028272 (speculation_ctrl_update+0x132/0x2c0)
> 	[    0.801823] Call Trace:
> 	[    0.801831]  ? seccomp_set_mode_filter+0x18d/0x800
> 	[    0.801833]  speculation_ctrl_update_current+0x21/0x30
> 	[    0.801837]  task_update_spec_tif+0x1d/0x20
> 	[    0.801839]  ssb_prctl_set+0xb5/0xd0
> 	[    0.801841]  arch_seccomp_spec_mitigate+0x2a/0x50
> 	[    0.801843]  seccomp_set_mode_filter+0x788/0x800
> 	[    0.801845]  do_seccomp+0x34/0x200
> 	[    0.801849]  __x64_sys_seccomp+0x15/0x20
> 	[    0.801852]  do_syscall_64+0x4a/0x1f0
> 	[    0.809349]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> 	[    0.810548] RIP: 0033:0x7f431db92e9d
> 	[    0.811528] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d b3 5f 0c 00 f7 d8 64 89 01 48
> 	[    0.814754] RSP: 002b:00007ffca5506788 EFLAGS: 00000246 ORIG_RAX: 000000000000013d
> 	[    0.816075] RAX: ffffffffffffffda RBX: 0000556956c07580 RCX: 00007f431db92e9d
> 	[    0.817367] RDX: 0000556956c023e0 RSI: 0000000000000000 RDI: 0000000000000001
> 	[    0.818698] RBP: 0000556956c023e0 R08: 0000000000000007 R09: 0000556956b73730
> 	[    0.819948] R10: 0000556956b7101a R11: 0000000000000246 R12: 000000000000002d
> 	[    0.821184] R13: 0040000000002001 R14: 00007f431d9b4898 R15: 0000000000000000
> 
> The VM still boots though.
> 
> I've actually been seeing this for a while but haven't had a chance to bisect it
> until now.
> 
> Reverting the commit (4c6903a0f9d76) on mainline makes the warnings go away.
> 
> Any ideas?  Presumably something isn't working as intended.
> 

Ping.

^ permalink raw reply	[flat|nested] 14+ messages in thread

end of thread, back to index

Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-08-21  8:26 [PATCH v2 0/3] KVM: x86: fixes for speculation bug feature reporting Paolo Bonzini
2019-08-21  8:26 ` [PATCH 1/3] KVM: x86: fix reporting of AMD speculation bug CPUID leaf Paolo Bonzini
2019-08-21 19:45   ` Jim Mattson
2019-08-22 18:46   ` Konrad Rzeszutek Wilk
2019-11-30 23:27   ` Eric Biggers
2019-12-09 17:55     ` Eric Biggers
2019-08-21  8:26 ` [PATCH 2/3] KVM: x86: always expose VIRT_SSBD to guests Paolo Bonzini
2019-08-21 19:47   ` Jim Mattson
2019-08-22 18:44   ` Konrad Rzeszutek Wilk
2019-10-01 22:16   ` Eduardo Habkost
2019-10-06 16:08     ` Paolo Bonzini
2019-08-21  8:26 ` [PATCH 3/3] KVM: x86: use Intel speculation bugs and features as derived in generic x86 code Paolo Bonzini
2019-08-21 19:48   ` Jim Mattson
2019-08-22 18:45   ` Konrad Rzeszutek Wilk

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