Re: [PATCH] KVM: Fix MAXPHYADDR calculation when cpuid does not support it
On 04/11/2010 03:33 PM, Avi Kivity wrote: MAXPHYADDR is derived from cpuid 0x8008, but when that isn't present, we get some random value. Fix by checking first that cpuid 0x8008 is supported. Pekka Enbergpenb...@cs.helsinki.fi ^ += Reported-by: (looking forward to Tested-by: too) -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] KVM: Fix MAXPHYADDR calculation when cpuid does not support it
Avi Kivity wrote:
MAXPHYADDR is derived from cpuid 0x8008, but when that isn't present, we
get some random value.
Fix by checking first that cpuid 0x8008 is supported.
Pekka Enberg penb...@cs.helsinki.fi
Signed-off-by: Avi Kivity a...@redhat.com
---
arch/x86/kvm/x86.c |4
1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fd5c3d3..b2460cd 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4165,9 +4165,13 @@ int cpuid_maxphyaddr(struct kvm_vcpu *vcpu)
{
struct kvm_cpuid_entry2 *best;
+ best = kvm_find_cpuid_entry(vcpu, 0x8000, 0);
+ if (!best || best-eax 0x8008)
+ goto not_found;
best = kvm_find_cpuid_entry(vcpu, 0x8008, 0);
if (best)
return best-eax 0xff;
+not_found:
return 36;
}
Hmm, doesn't seem to work here. I still that triple fault in guest.
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Re: [PATCH] KVM: Fix MAXPHYADDR calculation when cpuid does not support it
On 04/11/2010 04:32 PM, Pekka Enberg wrote:
Avi Kivity wrote:
MAXPHYADDR is derived from cpuid 0x8008, but when that isn't
present, we
get some random value.
Fix by checking first that cpuid 0x8008 is supported.
Pekka Enberg penb...@cs.helsinki.fi
Signed-off-by: Avi Kivity a...@redhat.com
---
arch/x86/kvm/x86.c |4
1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fd5c3d3..b2460cd 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4165,9 +4165,13 @@ int cpuid_maxphyaddr(struct kvm_vcpu *vcpu)
{
struct kvm_cpuid_entry2 *best;
+best = kvm_find_cpuid_entry(vcpu, 0x8000, 0);
+if (!best || best-eax 0x8008)
+goto not_found;
best = kvm_find_cpuid_entry(vcpu, 0x8008, 0);
if (best)
return best-eax 0xff;
+not_found:
return 36;
}
Hmm, doesn't seem to work here. I still that triple fault in guest.
Can you add a printk to see what value is returned and why?
--
error compiling committee.c: too many arguments to function
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Re: [PATCH] KVM: Fix MAXPHYADDR calculation when cpuid does not support it
Avi Kivity wrote: Hmm, doesn't seem to work here. I still that triple fault in guest. Can you add a printk to see what value is returned and why? Argh, it's a off-by one bug in my userspace tool... So the CPU really does support 0x8008 and I'm just an idiot. :-) Pekka -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] KVM: Fix MAXPHYADDR calculation when cpuid does not support it
Pekka Enberg wrote: Avi Kivity wrote: Hmm, doesn't seem to work here. I still that triple fault in guest. Can you add a printk to see what value is returned and why? Argh, it's a off-by one bug in my userspace tool... So the CPU really does support 0x8008 and I'm just an idiot. :-) So to explain this a bit more: I'm setting 0x8000 to 0x8008 but failing to install an entry for 0x8008. I don't quite understand why kvm_find_cpuid_entry() doesn't return NULL in this case? Pekka -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] KVM: Fix MAXPHYADDR calculation when cpuid does not support it
On 04/11/2010 04:45 PM, Pekka Enberg wrote: Pekka Enberg wrote: Avi Kivity wrote: Hmm, doesn't seem to work here. I still that triple fault in guest. Can you add a printk to see what value is returned and why? Argh, it's a off-by one bug in my userspace tool... So the CPU really does support 0x8008 and I'm just an idiot. :-) So to explain this a bit more: I'm setting 0x8000 to 0x8008 but failing to install an entry for 0x8008. I don't quite understand why kvm_find_cpuid_entry() doesn't return NULL in this case? cpuid is defined to return the highest entry if it doesn't find a match. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] KVM: Fix MAXPHYADDR calculation when cpuid does not support it
Avi Kivity wrote: On 04/11/2010 04:45 PM, Pekka Enberg wrote: Pekka Enberg wrote: Avi Kivity wrote: Hmm, doesn't seem to work here. I still that triple fault in guest. Can you add a printk to see what value is returned and why? Argh, it's a off-by one bug in my userspace tool... So the CPU really does support 0x8008 and I'm just an idiot. :-) So to explain this a bit more: I'm setting 0x8000 to 0x8008 but failing to install an entry for 0x8008. I don't quite understand why kvm_find_cpuid_entry() doesn't return NULL in this case? cpuid is defined to return the highest entry if it doesn't find a match. OK, then it's a bug of my own doing and we don't need to do anything in the kernel. Pekka -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] KVM: Fix MAXPHYADDR calculation when cpuid does not support it
On 04/11/2010 04:53 PM, Pekka Enberg wrote: Avi Kivity wrote: On 04/11/2010 04:45 PM, Pekka Enberg wrote: Pekka Enberg wrote: Avi Kivity wrote: Hmm, doesn't seem to work here. I still that triple fault in guest. Can you add a printk to see what value is returned and why? Argh, it's a off-by one bug in my userspace tool... So the CPU really does support 0x8008 and I'm just an idiot. :-) So to explain this a bit more: I'm setting 0x8000 to 0x8008 but failing to install an entry for 0x8008. I don't quite understand why kvm_find_cpuid_entry() doesn't return NULL in this case? cpuid is defined to return the highest entry if it doesn't find a match. OK, then it's a bug of my own doing and we don't need to do anything in the kernel. I think the patch is nevertheless correct, not sure why it worked so far. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] KVM: Fix MAXPHYADDR calculation when cpuid does not support it
Avi Kivity wrote: OK, then it's a bug of my own doing and we don't need to do anything in the kernel. I think the patch is nevertheless correct, not sure why it worked so far. Yes, agreed. I'm guessing most 64-bit CPUs support 0x8008 and qemu does the right thing so the bug doesn't trigger in practice. Acked-by: Pekka Enberg penb...@cs.helsinki.fi -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
