EFER reserved bits are statically initialized, and do not reset if a vendor module is re-loaded. For example, loading kvm_amd with nested=1 removes EFER.SVME (and potentially EFER.LMSLE) from the reserved bits. Reloading kvm_amd with nested=0 does not add them back, allowing userspace to set EFER.SVME with nested=0. Re-initializing EFER reserved bits before configuring them on vendor initialization. Cc: stable@vger.kernel.org Signed-off-by: Yosry Ahmed --- arch/x86/kvm/msrs.c | 10 ++++++++-- arch/x86/kvm/msrs.h | 1 + arch/x86/kvm/x86.c | 2 ++ 3 files changed, 11 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/msrs.c b/arch/x86/kvm/msrs.c index 67481429ad6b8..a7394bdae0295 100644 --- a/arch/x86/kvm/msrs.c +++ b/arch/x86/kvm/msrs.c @@ -19,8 +19,7 @@ bool __read_mostly report_ignored_msrs = true; module_param(report_ignored_msrs, bool, 0644); EXPORT_SYMBOL_FOR_KVM_INTERNAL(report_ignored_msrs); -/* Enable syscall by default because its emulated by KVM */ -static u64 __read_mostly efer_reserved_bits = ~((u64)EFER_SCE); +static u64 __read_mostly efer_reserved_bits; #define MAX_IO_MSRS 256 @@ -650,6 +649,13 @@ static int set_efer(struct kvm_vcpu *vcpu, struct msr_data *msr_info) return 0; } +void kvm_init_efer_bits(void) +{ + /* Enable syscall by default because its emulated by KVM */ + efer_reserved_bits = ~((u64)EFER_SCE); +} +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_init_efer_bits); + void kvm_enable_efer_bits(u64 mask) { efer_reserved_bits &= ~mask; diff --git a/arch/x86/kvm/msrs.h b/arch/x86/kvm/msrs.h index 9c5c6b33e58f5..1f772e1717588 100644 --- a/arch/x86/kvm/msrs.h +++ b/arch/x86/kvm/msrs.h @@ -58,6 +58,7 @@ int kvm_get_set_one_reg(struct kvm_vcpu *vcpu, unsigned int ioctl, int kvm_get_reg_list(struct kvm_vcpu *vcpu, struct kvm_reg_list __user *user_list); +void kvm_init_efer_bits(void); void kvm_enable_efer_bits(u64); bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer); int kvm_emulate_msr_read(struct kvm_vcpu *vcpu, u32 index, u64 *data); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index f68424a985cda..83f608dad0605 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6913,6 +6913,8 @@ EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_setup_xss_caps); static void kvm_setup_efer_caps(void) { + kvm_init_efer_bits(); + if (kvm_cpu_cap_has(X86_FEATURE_LM)) kvm_enable_efer_bits(EFER_LME | EFER_LMA); -- 2.55.0.141.g00534a21ce-goog