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| author | Aaron Lewis <aaronlewis@google.com> | 2023-04-05 02:45:15 +0200 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2023-04-11 19:19:03 +0200 |
| commit | 6be3ae45f567cdebb5b9938137bf3445ceacf9fb (patch) | |
| tree | 84ecd4be65938442d421322bd51d8bc7c4be5dc2 /arch/x86/kvm/x86.h | |
| parent | KVM: selftests: Close opened file descriptor in stable_tsc_check_supported() (diff) | |
| download | linux-6be3ae45f567cdebb5b9938137bf3445ceacf9fb.tar.xz linux-6be3ae45f567cdebb5b9938137bf3445ceacf9fb.zip | |
KVM: x86: Add a helper to handle filtering of unpermitted XCR0 features
Add a helper, kvm_get_filtered_xcr0(), to dedup code that needs to account
for XCR0 features that require explicit opt-in on a per-process basis. In
addition to documenting when KVM should/shouldn't consult
xstate_get_guest_group_perm(), the helper will also allow sanitizing the
filtered XCR0 to avoid enumerating architecturally illegal XCR0 values,
e.g. XTILE_CFG without XTILE_DATA.
No functional changes intended.
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
[sean: rename helper, move to x86.h, massage changelog]
Reviewed-by: Aaron Lewis <aaronlewis@google.com>
Tested-by: Aaron Lewis <aaronlewis@google.com>
Link: https://lore.kernel.org/r/20230405004520.421768-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'arch/x86/kvm/x86.h')
| -rw-r--r-- | arch/x86/kvm/x86.h | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index a8167b47b8c8..9589c86812eb 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -315,6 +315,19 @@ extern struct kvm_caps kvm_caps; extern bool enable_pmu; +/* + * Get a filtered version of KVM's supported XCR0 that strips out dynamic + * features for which the current process doesn't (yet) have permission to use. + * This is intended to be used only when enumerating support to userspace, + * e.g. in KVM_GET_SUPPORTED_CPUID and KVM_CAP_XSAVE2, it does NOT need to be + * used to check/restrict guest behavior as KVM rejects KVM_SET_CPUID{2} if + * userspace attempts to enable unpermitted features. + */ +static inline u64 kvm_get_filtered_xcr0(void) +{ + return kvm_caps.supported_xcr0 & xstate_get_guest_group_perm(); +} + static inline bool kvm_mpx_supported(void) { return (kvm_caps.supported_xcr0 & (XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR)) |