On Tue, 2018-01-09 at 23:44 +1100, Alexey Kardashevskiy wrote: > On 09/01/18 19:39, Suraj Jitindar Singh wrote: > > On Tue, 2018-01-09 at 15:48 +1100, Paul Mackerras wrote: > > > This adds three new capabilities that give userspace information > > > about > > > the underlying machine's level of vulnerability to the Meltdown > > > and > > > Spectre attacks, and what instructions the hardware implements to > > > assist software to work around the vulnerabilities. > > > > > > Each capability is a tri-state, where 0 indicates that the > > > machine is > > > vulnerable and no workarounds are implement, 1 indicates that the > > > machine is vulnerable but workaround assist instructions are > > > available, and 2 indicates that the machine is not vulnerable. > > > > > > The capabilities are: > > > > > > KVM_CAP_PPC_SAFE_CACHE reports the vulnerability of the machine > > > to > > > attacks based on using speculative loads to data in L1 cache > > > which > > > should not be addressable. The workaround provided by hardware > > > is an > > > instruction to invalidate the entire L1 data cache. > > > > > > KVM_CAP_PPC_SAFE_BOUNDS_CHECK reports the vulnerability of the > > > machine > > > to attacks based on using speculative loads behind mispredicted > > > bounds > > > checks. The workaround provided by hardware is an instruction > > > that > > > acts as a speculation barrier. > > > > > > KVM_CAP_PPC_SAFE_INDIRECT_BRANCH reports the vulnerability of the > > > machine to attacks based on poisoning the indirect branch > > > predictor. > > > No workaround that requires software changes is provided; the > > > current > > > hardware fix is to prevent speculation past indirect branches. > > > > > > Signed-off-by: Paul Mackerras <paulus@xxxxxxxxxx> > > > --- > > > Note: This patch depends on the patch "powerpc/pseries: Add > > > H_GET_CPU_CHARACTERISTICS flags & wrapper" by Michael Ellerman, > > > available at http://patchwork.ozlabs.org/patch/856914/ . > > > > > > Documentation/virtual/kvm/api.txt | 36 +++++++ > > > arch/powerpc/kvm/powerpc.c | 202 > > > ++++++++++++++++++++++++++++++++++++++ > > > include/uapi/linux/kvm.h | 3 + > > > 3 files changed, 241 insertions(+) > > > > > > diff --git a/Documentation/virtual/kvm/api.txt > > > b/Documentation/virtual/kvm/api.txt > > > index 57d3ee9..8d76260 100644 > > > --- a/Documentation/virtual/kvm/api.txt > > > +++ b/Documentation/virtual/kvm/api.txt > > > @@ -4369,3 +4369,39 @@ Parameters: none > > > This capability indicates if the flic device will be able to > > > get/set > > > the > > > AIS states for migration via the KVM_DEV_FLIC_AISM_ALL attribute > > > and > > > allows > > > to discover this without having to create a flic device. > > > + > > > +8.14 KVM_CAP_PPC_SAFE_CACHE > > > + > > > +Architectures: ppc > > > + > > > +This capability gives information about the underlying machine's > > > +vulnerability or otherwise to the Meltdown attack. Its value is > > > a > > > +tristate, where 0 indicates the machine is vulnerable, 1 > > > indicates > > > the > > > +hardware is vulnerable but provides assistance to work around > > > the > > > +vulnerability (specifically by providing a fast L1 data cache > > > flush > > > +facility), and 2 indicates that the machine is not vulnerable. > > > + > > > +8.15 KVM_CAP_PPC_SAFE_BOUNDS_CHECK > > > + > > > +Architectures: ppc > > > + > > > +This capability gives information about the underlying machine's > > > +vulnerability or otherwise to the bounds-check variant of the > > > Spectre > > > +attack. Its value is a tristate, where 0 indicates the machine > > > is > > > +vulnerable, 1 indicates the hardware is vulnerable but provides > > > +assistance to work around the vulnerability (specifically by > > > providing > > > +an instruction that acts as a speculation barrier), and 2 > > > indicates > > > +that the machine is not vulnerable. > > > + > > > +8.16 KVM_CAP_PPC_SAFE_INDIRECT_BRANCH > > > + > > > +Architectures: ppc > > > + > > > +This capability gives information about the underlying machine's > > > +vulnerability or otherwise to the indirect branch variant of the > > > Spectre > > > +attack. Its value is a tristate, where 0 indicates the machine > > > is > > > +vulnerable and 2 indicates that the machine is not vulnerable. > > > +(1 would indicate the availability of a workaround that software > > > +needs to implement, but there is currently no workaround that > > > needs > > > +software changes.) > > > + > > > diff --git a/arch/powerpc/kvm/powerpc.c > > > b/arch/powerpc/kvm/powerpc.c > > > index 1915e86..58e863b 100644 > > > --- a/arch/powerpc/kvm/powerpc.c > > > +++ b/arch/powerpc/kvm/powerpc.c > > > @@ -39,6 +39,10 @@ > > > #include <asm/iommu.h> > > > #include <asm/switch_to.h> > > > #include <asm/xive.h> > > > +#ifdef CONFIG_PPC_PSERIES > > > +#include <asm/hvcall.h> > > > +#include <asm/plpar_wrappers.h> > > > +#endif > > > > > > #include "timing.h" > > > #include "irq.h" > > > @@ -488,6 +492,193 @@ void kvm_arch_destroy_vm(struct kvm *kvm) > > > module_put(kvm->arch.kvm_ops->owner); > > > } > > > > > > +#ifdef CONFIG_PPC_BOOK3S_64 > > > +/* > > > + * These functions check whether the underlying hardware is safe > > > + * against the Meltdown/Spectre attacks and whether it supplies > > > + * instructions for use in workarounds. The information comes > > > from > > > + * firmware, either via the device tree on powernv platforms or > > > + * from an hcall on pseries platforms. > > > + * > > > + * For check_safe_cache() and check_safe_bounds_check(), a > > > return > > > + * value of 0 means vulnerable, 1 means vulnerable but > > > workaround > > > + * instructions are provided, and 2 means not vulnerable (no > > > workaround > > > + * is needed). > > > + * For check_safe_indirect_branch(), 0 means vulnerable and 2 > > > means > > > + * not vulnerable. > > > + */ > > > +static inline bool have_fw_feat(struct device_node *fw_features, > > > + const char *state, const char > > > *name) > > > +{ > > > + struct device_node *np; > > > + bool r = false; > > > + > > > + np = of_get_child_by_name(fw_features, name); > > > + if (np) { > > > + r = of_property_read_bool(np, state); > > > + of_node_put(np); > > > + } > > > + return r; > > > +} > > > + > > > +#ifdef CONFIG_PPC_PSERIES > > > +static bool check_pseries_safe_cache(int *rp) > > > +{ > > > + struct h_cpu_char_result c; > > > + unsigned long rc; > > > + int r = 0; > > > + > > > + if (!machine_is(pseries)) > > > + return false; > > > + > > > + rc = plpar_get_cpu_characteristics(&c); > > > + if (rc == H_SUCCESS) { > > > + if (!(c.behavior & > > > > s/behavior/behaviour > Mainly because that's what it's called in the struct and so needs to be that if you want it to compile :) Also, straya > Why? > https://dictionary.cambridge.org/dictionary/english/behavior > > > -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
