* [PATCH] KVM: selftests: x86: Prioritize getting max_gfn from GuestPhysBits
@ 2024-05-08 6:42 Tao Su
2024-05-08 14:09 ` Sean Christopherson
0 siblings, 1 reply; 3+ messages in thread
From: Tao Su @ 2024-05-08 6:42 UTC (permalink / raw)
To: kvm; +Cc: seanjc, pbonzini, chao.gao, xiaoyao.li, tao1.su
Use the max mappable GPA via GuestPhysBits advertised by KVM to calculate
max_gfn. Currently some selftests (e.g. access_tracking_perf_test,
dirty_log_test...) add RAM regions close to max_gfn, so guest may access
GPA beyond its mappable range and cause infinite loop.
Prioritize obtaining pa_bits from the GuestPhysBits field advertised by
KVM, so max_gfn can be limited to the mappable range.
Signed-off-by: Tao Su <tao1.su@linux.intel.com>
---
This patch is based on https://github.com/kvm-x86/linux/commit/b628cb523c65
---
tools/testing/selftests/kvm/include/x86_64/processor.h | 1 +
tools/testing/selftests/kvm/lib/x86_64/processor.c | 4 +++-
2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 81ce37ec407d..ff99f66d81a0 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -282,6 +282,7 @@ struct kvm_x86_cpu_property {
#define X86_PROPERTY_MAX_EXT_LEAF KVM_X86_CPU_PROPERTY(0x80000000, 0, EAX, 0, 31)
#define X86_PROPERTY_MAX_PHY_ADDR KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 0, 7)
#define X86_PROPERTY_MAX_VIRT_ADDR KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 8, 15)
+#define X86_PROPERTY_MAX_GUEST_PHY_ADDR KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 16, 23)
#define X86_PROPERTY_SEV_C_BIT KVM_X86_CPU_PROPERTY(0x8000001F, 0, EBX, 0, 5)
#define X86_PROPERTY_PHYS_ADDR_REDUCTION KVM_X86_CPU_PROPERTY(0x8000001F, 0, EBX, 6, 11)
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index 74a4c736c9ae..6c69f1dfeed2 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -1074,7 +1074,9 @@ void kvm_get_cpu_address_width(unsigned int *pa_bits, unsigned int *va_bits)
*pa_bits = kvm_cpu_has(X86_FEATURE_PAE) ? 36 : 32;
*va_bits = 32;
} else {
- *pa_bits = kvm_cpu_property(X86_PROPERTY_MAX_PHY_ADDR);
+ *pa_bits = kvm_cpu_property(X86_PROPERTY_MAX_GUEST_PHY_ADDR);
+ if (*pa_bits == 0)
+ *pa_bits = kvm_cpu_property(X86_PROPERTY_MAX_PHY_ADDR);
*va_bits = kvm_cpu_property(X86_PROPERTY_MAX_VIRT_ADDR);
}
}
base-commit: dccb07f2914cdab2ac3a5b6c98406f765acab803
--
2.34.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] KVM: selftests: x86: Prioritize getting max_gfn from GuestPhysBits
2024-05-08 6:42 [PATCH] KVM: selftests: x86: Prioritize getting max_gfn from GuestPhysBits Tao Su
@ 2024-05-08 14:09 ` Sean Christopherson
2024-05-09 5:12 ` Tao Su
0 siblings, 1 reply; 3+ messages in thread
From: Sean Christopherson @ 2024-05-08 14:09 UTC (permalink / raw)
To: Tao Su; +Cc: kvm, pbonzini, chao.gao, xiaoyao.li
On Wed, May 08, 2024, Tao Su wrote:
> Use the max mappable GPA via GuestPhysBits advertised by KVM to calculate
> max_gfn. Currently some selftests (e.g. access_tracking_perf_test,
> dirty_log_test...) add RAM regions close to max_gfn, so guest may access
> GPA beyond its mappable range and cause infinite loop.
>
> Prioritize obtaining pa_bits from the GuestPhysBits field advertised by
> KVM, so max_gfn can be limited to the mappable range.
>
> Signed-off-by: Tao Su <tao1.su@linux.intel.com>
> ---
> This patch is based on https://github.com/kvm-x86/linux/commit/b628cb523c65
> ---
> tools/testing/selftests/kvm/include/x86_64/processor.h | 1 +
> tools/testing/selftests/kvm/lib/x86_64/processor.c | 4 +++-
> 2 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
> index 81ce37ec407d..ff99f66d81a0 100644
> --- a/tools/testing/selftests/kvm/include/x86_64/processor.h
> +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
> @@ -282,6 +282,7 @@ struct kvm_x86_cpu_property {
> #define X86_PROPERTY_MAX_EXT_LEAF KVM_X86_CPU_PROPERTY(0x80000000, 0, EAX, 0, 31)
> #define X86_PROPERTY_MAX_PHY_ADDR KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 0, 7)
> #define X86_PROPERTY_MAX_VIRT_ADDR KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 8, 15)
> +#define X86_PROPERTY_MAX_GUEST_PHY_ADDR KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 16, 23)
> #define X86_PROPERTY_SEV_C_BIT KVM_X86_CPU_PROPERTY(0x8000001F, 0, EBX, 0, 5)
> #define X86_PROPERTY_PHYS_ADDR_REDUCTION KVM_X86_CPU_PROPERTY(0x8000001F, 0, EBX, 6, 11)
>
> diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> index 74a4c736c9ae..6c69f1dfeed2 100644
> --- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
> +++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> @@ -1074,7 +1074,9 @@ void kvm_get_cpu_address_width(unsigned int *pa_bits, unsigned int *va_bits)
> *pa_bits = kvm_cpu_has(X86_FEATURE_PAE) ? 36 : 32;
> *va_bits = 32;
> } else {
> - *pa_bits = kvm_cpu_property(X86_PROPERTY_MAX_PHY_ADDR);
> + *pa_bits = kvm_cpu_property(X86_PROPERTY_MAX_GUEST_PHY_ADDR);
> + if (*pa_bits == 0)
> + *pa_bits = kvm_cpu_property(X86_PROPERTY_MAX_PHY_ADDR);
This is the wrong place to incorporaate the max mappable GPA. The pa_bits field
should reflect the "real" MAXPHYADDR, it's vm->max_gfn that needs to be adjusted,
and x86 selftests already overrides vm_compute_max_gfn() specifically to deal with
goofy edge cases like this.
> *va_bits = kvm_cpu_property(X86_PROPERTY_MAX_VIRT_ADDR);
> }
> }
>
> base-commit: dccb07f2914cdab2ac3a5b6c98406f765acab803
> --
> 2.34.1
>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] KVM: selftests: x86: Prioritize getting max_gfn from GuestPhysBits
2024-05-08 14:09 ` Sean Christopherson
@ 2024-05-09 5:12 ` Tao Su
0 siblings, 0 replies; 3+ messages in thread
From: Tao Su @ 2024-05-09 5:12 UTC (permalink / raw)
To: Sean Christopherson; +Cc: kvm, pbonzini, chao.gao, xiaoyao.li
On Wed, May 08, 2024 at 07:09:48AM -0700, Sean Christopherson wrote:
> On Wed, May 08, 2024, Tao Su wrote:
> > Use the max mappable GPA via GuestPhysBits advertised by KVM to calculate
> > max_gfn. Currently some selftests (e.g. access_tracking_perf_test,
> > dirty_log_test...) add RAM regions close to max_gfn, so guest may access
> > GPA beyond its mappable range and cause infinite loop.
> >
> > Prioritize obtaining pa_bits from the GuestPhysBits field advertised by
> > KVM, so max_gfn can be limited to the mappable range.
> >
> > Signed-off-by: Tao Su <tao1.su@linux.intel.com>
> > ---
> > This patch is based on https://github.com/kvm-x86/linux/commit/b628cb523c65
> > ---
> > tools/testing/selftests/kvm/include/x86_64/processor.h | 1 +
> > tools/testing/selftests/kvm/lib/x86_64/processor.c | 4 +++-
> > 2 files changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
> > index 81ce37ec407d..ff99f66d81a0 100644
> > --- a/tools/testing/selftests/kvm/include/x86_64/processor.h
> > +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
> > @@ -282,6 +282,7 @@ struct kvm_x86_cpu_property {
> > #define X86_PROPERTY_MAX_EXT_LEAF KVM_X86_CPU_PROPERTY(0x80000000, 0, EAX, 0, 31)
> > #define X86_PROPERTY_MAX_PHY_ADDR KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 0, 7)
> > #define X86_PROPERTY_MAX_VIRT_ADDR KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 8, 15)
> > +#define X86_PROPERTY_MAX_GUEST_PHY_ADDR KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 16, 23)
> > #define X86_PROPERTY_SEV_C_BIT KVM_X86_CPU_PROPERTY(0x8000001F, 0, EBX, 0, 5)
> > #define X86_PROPERTY_PHYS_ADDR_REDUCTION KVM_X86_CPU_PROPERTY(0x8000001F, 0, EBX, 6, 11)
> >
> > diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> > index 74a4c736c9ae..6c69f1dfeed2 100644
> > --- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
> > +++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> > @@ -1074,7 +1074,9 @@ void kvm_get_cpu_address_width(unsigned int *pa_bits, unsigned int *va_bits)
> > *pa_bits = kvm_cpu_has(X86_FEATURE_PAE) ? 36 : 32;
> > *va_bits = 32;
> > } else {
> > - *pa_bits = kvm_cpu_property(X86_PROPERTY_MAX_PHY_ADDR);
> > + *pa_bits = kvm_cpu_property(X86_PROPERTY_MAX_GUEST_PHY_ADDR);
> > + if (*pa_bits == 0)
> > + *pa_bits = kvm_cpu_property(X86_PROPERTY_MAX_PHY_ADDR);
>
> This is the wrong place to incorporaate the max mappable GPA. The pa_bits field
> should reflect the "real" MAXPHYADDR, it's vm->max_gfn that needs to be adjusted,
> and x86 selftests already overrides vm_compute_max_gfn() specifically to deal with
> goofy edge cases like this.
Thanks for pointing out! I will adjust max_gfn in the vm_compute_max_gfn() overrided
by x86 selftests.
>
> > *va_bits = kvm_cpu_property(X86_PROPERTY_MAX_VIRT_ADDR);
> > }
> > }
> >
> > base-commit: dccb07f2914cdab2ac3a5b6c98406f765acab803
> > --
> > 2.34.1
> >
^ permalink raw reply [flat|nested] 3+ messages in thread
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2024-05-08 6:42 [PATCH] KVM: selftests: x86: Prioritize getting max_gfn from GuestPhysBits Tao Su
2024-05-08 14:09 ` Sean Christopherson
2024-05-09 5:12 ` Tao Su
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