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authorSean Christopherson <seanjc@google.com>2021-05-05 01:56:31 +0300
committerThomas Gleixner <tglx@linutronix.de>2021-05-05 22:50:14 +0300
commitb6b4fbd90b155a0025223df2c137af8a701d53b3 (patch)
tree3256305917ffbed009f9e651956c9b88fa3e8ef4 /arch
parent4029b9706d53e5e8db2e1cee6ecd75e60b62cd09 (diff)
downloadlinux-b6b4fbd90b155a0025223df2c137af8a701d53b3.tar.xz
x86/cpu: Initialize MSR_TSC_AUX if RDTSCP *or* RDPID is supported
Initialize MSR_TSC_AUX with CPU node information if RDTSCP or RDPID is supported. This fixes a bug where vdso_read_cpunode() will read garbage via RDPID if RDPID is supported but RDTSCP is not. While no known CPU supports RDPID but not RDTSCP, both Intel's SDM and AMD's APM allow for RDPID to exist without RDTSCP, e.g. it's technically a legal CPU model for a virtual machine. Note, technically MSR_TSC_AUX could be initialized if and only if RDPID is supported since RDTSCP is currently not used to retrieve the CPU node. But, the cost of the superfluous WRMSR is negigible, whereas leaving MSR_TSC_AUX uninitialized is just asking for future breakage if someone decides to utilize RDTSCP. Fixes: a582c540ac1b ("x86/vdso: Use RDPID in preference to LSL when available") Signed-off-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20210504225632.1532621-2-seanjc@google.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 6bdb69a9a7dc..490bed07fe35 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1851,7 +1851,7 @@ static inline void setup_getcpu(int cpu)
unsigned long cpudata = vdso_encode_cpunode(cpu, early_cpu_to_node(cpu));
struct desc_struct d = { };
- if (boot_cpu_has(X86_FEATURE_RDTSCP))
+ if (boot_cpu_has(X86_FEATURE_RDTSCP) || boot_cpu_has(X86_FEATURE_RDPID))
write_rdtscp_aux(cpudata);
/* Store CPU and node number in limit. */