| Message ID | 20240508064205.15301-1-tao1.su@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: selftests: x86: Prioritize getting max_gfn from GuestPhysBits | expand |
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 >
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 > >
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); } }
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(-) base-commit: dccb07f2914cdab2ac3a5b6c98406f765acab803