On Mon, Mar 01, 2021 at 10:45:02PM +1300, Kai Huang wrote:
> From: Sean Christopherson <[email protected]>
>
> The kernel will currently disable all SGX support if the hardware does
> not support launch control. Make it more permissive to allow SGX
> virtualization on systems without Launch Control support. This will
> allow KVM to expose SGX to guests that have less-strict requirements on
> the availability of flexible launch control.
>
> Improve error message to distinguish between three cases. There are two
> cases where SGX support is completely disabled:
> 1) SGX has been disabled completely by the BIOS
> 2) SGX LC is locked by the BIOS. Bare-metal support is disabled because
> of LC unavailability. SGX virtualization is unavailable (because of
> Kconfig).
> One where it is partially available:
> 3) SGX LC is locked by the BIOS. Bare-metal support is disabled because
> of LC unavailability. SGX virtualization is supported.
>
> Signed-off-by: Sean Christopherson <[email protected]>
> Co-developed-by: Kai Huang <[email protected]>
> Acked-by: Dave Hansen <[email protected]>
> Signed-off-by: Kai Huang <[email protected]>
> ---
> arch/x86/kernel/cpu/feat_ctl.c | 57 ++++++++++++++++++++++++++--------
> 1 file changed, 44 insertions(+), 13 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/feat_ctl.c b/arch/x86/kernel/cpu/feat_ctl.c
> index 27533a6e04fa..96c370284913 100644
> --- a/arch/x86/kernel/cpu/feat_ctl.c
> +++ b/arch/x86/kernel/cpu/feat_ctl.c
> @@ -105,7 +105,8 @@ early_param("nosgx", nosgx);
> void init_ia32_feat_ctl(struct cpuinfo_x86 *c)
> {
> bool tboot = tboot_enabled();
> - bool enable_sgx;
> + bool enable_sgx_any, enable_sgx_kvm, enable_sgx_driver;
> + bool enable_vmx;
> u64 msr;
The preferred ordering of variable declarations at the beginning of a
function is reverse fir tree order::
struct long_struct_name *descriptive_name;
unsigned long foo, bar;
unsigned int tmp;
int ret;
> if (rdmsrl_safe(MSR_IA32_FEAT_CTL, &msr)) {
> @@ -114,13 +115,21 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c)
> return;
> }
>
> + enable_vmx = cpu_has(c, X86_FEATURE_VMX) &&
> + IS_ENABLED(CONFIG_KVM_INTEL);
> +
> /*
> - * Enable SGX if and only if the kernel supports SGX and Launch Control
> - * is supported, i.e. disable SGX if the LE hash MSRs can't be written.
> + * Separate out SGX driver enabling from KVM. This allows KVM
> + * guests to use SGX even if the kernel SGX driver refuses to
> + * use it. This happens if flexible Faunch Control is not
> + * available.
> */
> - enable_sgx = cpu_has(c, X86_FEATURE_SGX) &&
> - cpu_has(c, X86_FEATURE_SGX_LC) &&
> - IS_ENABLED(CONFIG_X86_SGX);
> + enable_sgx_any = cpu_has(c, X86_FEATURE_SGX) &&
> + IS_ENABLED(CONFIG_X86_SGX);
> + enable_sgx_driver = enable_sgx_any &&
> + cpu_has(c, X86_FEATURE_SGX_LC);
> + enable_sgx_kvm = enable_sgx_any && enable_vmx &&
> + IS_ENABLED(CONFIG_X86_SGX_KVM);
That enable_sgx_any use looks weird. You can get rid of it:
if (cpu_has(c, X86_FEATURE_SGX) && IS_ENABLED(CONFIG_X86_SGX)) {
enable_sgx_driver = cpu_has(c, X86_FEATURE_SGX_LC);
enable_sgx_kvm = enable_vmx &&
IS_ENABLED(CONFIG_X86_SGX_KVM);
}
and yap, let longer lines stick out.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
