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authorSean Christopherson <sean.j.christopherson@intel.com>2020-02-26 15:16:15 -0800
committerBorislav Petkov <bp@suse.de>2020-02-27 19:02:45 +0100
commit735a6dd02222d8d070c7bb748f25895239ca8c92 (patch)
treee05e34eace70727bb57a0f5bfac8e3ef278a8b9c /arch
parentf8788d86ab28f61f7b46eb6be375f8a726783636 (diff)
x86/pkeys: Manually set X86_FEATURE_OSPKE to preserve existing changes
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
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/cpu/common.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 52c9bfbbdb2a..4cdb123ff66a 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -445,7 +445,7 @@ static __always_inline void setup_pku(struct cpuinfo_x86 *c)
* 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