| From 735a6dd02222d8d070c7bb748f25895239ca8c92 Mon Sep 17 00:00:00 2001 |
| From: Sean Christopherson <sean.j.christopherson@intel.com> |
| Date: Wed, 26 Feb 2020 15:16:15 -0800 |
| Subject: x86/pkeys: Manually set X86_FEATURE_OSPKE to preserve existing changes |
| |
| From: Sean Christopherson <sean.j.christopherson@intel.com> |
| |
| commit 735a6dd02222d8d070c7bb748f25895239ca8c92 upstream. |
| |
| Explicitly set X86_FEATURE_OSPKE via set_cpu_cap() instead of calling |
| get_cpu_cap() to pull the feature bit from CPUID after enabling CR4.PKE. |
| Invoking get_cpu_cap() effectively wipes out any {set,clear}_cpu_cap() |
| changes that were made between this_cpu->c_init() and setup_pku(), as |
| all non-synthetic feature words are reinitialized from the CPU's CPUID |
| values. |
| |
| Blasting away capability updates manifests most visibility when running |
| on a VMX capable CPU, but with VMX disabled by BIOS. To indicate that |
| VMX is disabled, init_ia32_feat_ctl() clears X86_FEATURE_VMX, using |
| clear_cpu_cap() instead of setup_clear_cpu_cap() so that KVM can report |
| which CPU is misconfigured (KVM needs to probe every CPU anyways). |
| Restoring X86_FEATURE_VMX from CPUID causes KVM to think VMX is enabled, |
| ultimately leading to an unexpected #GP when KVM attempts to do VMXON. |
| |
| Arguably, init_ia32_feat_ctl() should use setup_clear_cpu_cap() and let |
| KVM figure out a different way to report the misconfigured CPU, but VMX |
| is not the only feature bit that is affected, i.e. there is precedent |
| that tweaking feature bits via {set,clear}_cpu_cap() after ->c_init() |
| is expected to work. Most notably, x86_init_rdrand()'s clearing of |
| X86_FEATURE_RDRAND when RDRAND malfunctions is also overwritten. |
| |
| Fixes: 0697694564c8 ("x86/mm/pkeys: Actually enable Memory Protection Keys in the CPU") |
| Reported-by: Jacob Keller <jacob.e.keller@intel.com> |
| Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> |
| Signed-off-by: Borislav Petkov <bp@suse.de> |
| Acked-by: Dave Hansen <dave.hansen@linux.intel.com> |
| Tested-by: Jacob Keller <jacob.e.keller@intel.com> |
| Cc: stable@vger.kernel.org |
| Link: https://lkml.kernel.org/r/20200226231615.13664-1-sean.j.christopherson@intel.com |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/x86/kernel/cpu/common.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/arch/x86/kernel/cpu/common.c |
| +++ b/arch/x86/kernel/cpu/common.c |
| @@ -462,7 +462,7 @@ static __always_inline void setup_pku(st |
| * cpuid bit to be set. We need to ensure that we |
| * update that bit in this CPU's "cpu_info". |
| */ |
| - get_cpu_cap(c); |
| + set_cpu_cap(c, X86_FEATURE_OSPKE); |
| } |
| |
| #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS |