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| author | Sean Christopherson <sean.j.christopherson@intel.com> | 2020-02-26 15:16:15 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-03-11 18:03:04 +0100 |
| commit | a350eee14eca753114567d66ee1895187f9f40e6 (patch) | |
| tree | d6e6035b9872c7015bba4720e39cccc89de124c8 | |
| parent | a4719f6d07b2c63223f7452c435c5f578f105cfe (diff) | |
| download | linux-a350eee14eca753114567d66ee1895187f9f40e6.tar.gz linux-a350eee14eca753114567d66ee1895187f9f40e6.tar.bz2 linux-a350eee14eca753114567d66ee1895187f9f40e6.zip | |
x86/pkeys: Manually set X86_FEATURE_OSPKE to preserve existing changes
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>
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 3d805e8b3739..7b4141889919 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -360,7 +360,7 @@ 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 |