diff options
| author | Sean Christopherson <seanjc@google.com> | 2023-04-04 17:45:16 -0700 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2023-04-11 10:19:03 -0700 |
| commit | 55cd57b596e86140503214eafc8fb62c9c544e8f (patch) | |
| tree | d07ae7f768eaaafed257fc4434a35ab2d77ac67e /arch/x86/kvm/x86.h | |
| parent | 6be3ae45f567cdebb5b9938137bf3445ceacf9fb (diff) | |
KVM: x86: Filter out XTILE_CFG if XTILE_DATA isn't permitted
Filter out XTILE_CFG from the supported XCR0 reported to userspace if the
current process doesn't have access to XTILE_DATA. Attempting to set
XTILE_CFG in XCR0 will #GP if XTILE_DATA is also not set, and so keeping
XTILE_CFG as supported results in explosions if userspace feeds
KVM_GET_SUPPORTED_CPUID back into KVM and the guest doesn't sanity check
CPUID.
Fixes: 445ecdf79be0 ("kvm: x86: Exclude unpermitted xfeatures at KVM_GET_SUPPORTED_CPUID")
Reported-by: Aaron Lewis <aaronlewis@google.com>
Reviewed-by: Aaron Lewis <aaronlewis@google.com>
Tested-by: Aaron Lewis <aaronlewis@google.com>
Link: https://lore.kernel.org/r/20230405004520.421768-3-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 | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index 9589c86812eb..bca706406189 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -3,6 +3,7 @@ #define ARCH_X86_KVM_X86_H #include <linux/kvm_host.h> +#include <asm/fpu/xstate.h> #include <asm/mce.h> #include <asm/pvclock.h> #include "kvm_cache_regs.h" @@ -325,7 +326,22 @@ extern bool enable_pmu; */ static inline u64 kvm_get_filtered_xcr0(void) { - return kvm_caps.supported_xcr0 & xstate_get_guest_group_perm(); + u64 permitted_xcr0 = kvm_caps.supported_xcr0; + + BUILD_BUG_ON(XFEATURE_MASK_USER_DYNAMIC != XFEATURE_MASK_XTILE_DATA); + + if (permitted_xcr0 & XFEATURE_MASK_USER_DYNAMIC) { + permitted_xcr0 &= xstate_get_guest_group_perm(); + + /* + * Treat XTILE_CFG as unsupported if the current process isn't + * allowed to use XTILE_DATA, as attempting to set XTILE_CFG in + * XCR0 without setting XTILE_DATA is architecturally illegal. + */ + if (!(permitted_xcr0 & XFEATURE_MASK_XTILE_DATA)) + permitted_xcr0 &= ~XFEATURE_MASK_XTILE_CFG; + } + return permitted_xcr0; } static inline bool kvm_mpx_supported(void) |