5.10-stable review patch. If anyone has any objections, please let me know.
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From: Borislav Petkov bp@kernel.org
From: "Borislav Petkov (AMD)" bp@alien8.de
Commit f9af88a3d384c8b55beb5dc5483e5da0135fadbd upstream.
It will be used by other x86 mitigations.
No functional changes.
Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Reviewed-by: Pawan Gupta pawan.kumar.gupta@linux.intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst | 4 - arch/x86/entry/entry.S | 8 +- arch/x86/include/asm/irqflags.h | 4 - arch/x86/include/asm/mwait.h | 5 + arch/x86/include/asm/nospec-branch.h | 29 +++++----- arch/x86/kernel/cpu/bugs.c | 12 ++-- arch/x86/kvm/vmx/vmx.c | 2 7 files changed, 32 insertions(+), 32 deletions(-)
--- a/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst +++ b/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst @@ -157,9 +157,7 @@ This is achieved by using the otherwise combination with a microcode update. The microcode clears the affected CPU buffers when the VERW instruction is executed.
-Kernel reuses the MDS function to invoke the buffer clearing: - - mds_clear_cpu_buffers() +Kernel does the buffer clearing with x86_clear_cpu_buffers().
On MDS affected CPUs, the kernel already invokes CPU buffer clear on kernel/userspace, hypervisor/guest and C-state (idle) transitions. No --- a/arch/x86/entry/entry.S +++ b/arch/x86/entry/entry.S @@ -31,20 +31,20 @@ EXPORT_SYMBOL_GPL(entry_ibpb);
/* * Define the VERW operand that is disguised as entry code so that - * it can be referenced with KPTI enabled. This ensure VERW can be + * it can be referenced with KPTI enabled. This ensures VERW can be * used late in exit-to-user path after page tables are switched. */ .pushsection .entry.text, "ax"
.align L1_CACHE_BYTES, 0xcc -SYM_CODE_START_NOALIGN(mds_verw_sel) +SYM_CODE_START_NOALIGN(x86_verw_sel) UNWIND_HINT_EMPTY ANNOTATE_NOENDBR .word __KERNEL_DS .align L1_CACHE_BYTES, 0xcc -SYM_CODE_END(mds_verw_sel); +SYM_CODE_END(x86_verw_sel); /* For KVM */ -EXPORT_SYMBOL_GPL(mds_verw_sel); +EXPORT_SYMBOL_GPL(x86_verw_sel);
.popsection
--- a/arch/x86/include/asm/irqflags.h +++ b/arch/x86/include/asm/irqflags.h @@ -56,13 +56,13 @@ static __always_inline void native_irq_e
static inline __cpuidle void native_safe_halt(void) { - mds_idle_clear_cpu_buffers(); + x86_idle_clear_cpu_buffers(); asm volatile("sti; hlt": : :"memory"); }
static inline __cpuidle void native_halt(void) { - mds_idle_clear_cpu_buffers(); + x86_idle_clear_cpu_buffers(); asm volatile("hlt": : :"memory"); }
--- a/arch/x86/include/asm/mwait.h +++ b/arch/x86/include/asm/mwait.h @@ -43,7 +43,7 @@ static inline void __monitorx(const void
static inline void __mwait(unsigned long eax, unsigned long ecx) { - mds_idle_clear_cpu_buffers(); + x86_idle_clear_cpu_buffers();
/* "mwait %eax, %ecx;" */ asm volatile(".byte 0x0f, 0x01, 0xc9;" @@ -88,7 +88,8 @@ static inline void __mwaitx(unsigned lon
static inline void __sti_mwait(unsigned long eax, unsigned long ecx) { - mds_idle_clear_cpu_buffers(); + x86_idle_clear_cpu_buffers(); + /* "mwait %eax, %ecx;" */ asm volatile("sti; .byte 0x0f, 0x01, 0xc9;" :: "a" (eax), "c" (ecx)); --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -191,23 +191,23 @@ .endm
/* - * Macro to execute VERW instruction that mitigate transient data sampling - * attacks such as MDS. On affected systems a microcode update overloaded VERW - * instruction to also clear the CPU buffers. VERW clobbers CFLAGS.ZF. - * + * Macro to execute VERW insns that mitigate transient data sampling + * attacks such as MDS or TSA. On affected systems a microcode update + * overloaded VERW insns to also clear the CPU buffers. VERW clobbers + * CFLAGS.ZF. * Note: Only the memory operand variant of VERW clears the CPU buffers. */ .macro CLEAR_CPU_BUFFERS ALTERNATIVE "jmp .Lskip_verw_@", "", X86_FEATURE_CLEAR_CPU_BUF #ifdef CONFIG_X86_64 - verw mds_verw_sel(%rip) + verw x86_verw_sel(%rip) #else /* * In 32bit mode, the memory operand must be a %cs reference. The data * segments may not be usable (vm86 mode), and the stack segment may not * be flat (ESPFIX32). */ - verw %cs:mds_verw_sel + verw %cs:x86_verw_sel #endif .Lskip_verw_@: .endm @@ -398,22 +398,22 @@ DECLARE_STATIC_KEY_FALSE(switch_to_cond_ DECLARE_STATIC_KEY_FALSE(switch_mm_cond_ibpb); DECLARE_STATIC_KEY_FALSE(switch_mm_always_ibpb);
-DECLARE_STATIC_KEY_FALSE(mds_idle_clear); +DECLARE_STATIC_KEY_FALSE(cpu_buf_idle_clear);
DECLARE_STATIC_KEY_FALSE(mmio_stale_data_clear);
-extern u16 mds_verw_sel; +extern u16 x86_verw_sel;
#include <asm/segment.h>
/** - * mds_clear_cpu_buffers - Mitigation for MDS and TAA vulnerability + * x86_clear_cpu_buffers - Buffer clearing support for different x86 CPU vulns * * This uses the otherwise unused and obsolete VERW instruction in * combination with microcode which triggers a CPU buffer flush when the * instruction is executed. */ -static __always_inline void mds_clear_cpu_buffers(void) +static __always_inline void x86_clear_cpu_buffers(void) { static const u16 ds = __KERNEL_DS;
@@ -430,14 +430,15 @@ static __always_inline void mds_clear_cp }
/** - * mds_idle_clear_cpu_buffers - Mitigation for MDS vulnerability + * x86_idle_clear_cpu_buffers - Buffer clearing support in idle for the MDS + * vulnerability * * Clear CPU buffers if the corresponding static key is enabled */ -static inline void mds_idle_clear_cpu_buffers(void) +static __always_inline void x86_idle_clear_cpu_buffers(void) { - if (static_branch_likely(&mds_idle_clear)) - mds_clear_cpu_buffers(); + if (static_branch_likely(&cpu_buf_idle_clear)) + x86_clear_cpu_buffers(); }
#endif /* __ASSEMBLY__ */ --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -118,9 +118,9 @@ DEFINE_STATIC_KEY_FALSE(switch_mm_cond_i /* Control unconditional IBPB in switch_mm() */ DEFINE_STATIC_KEY_FALSE(switch_mm_always_ibpb);
-/* Control MDS CPU buffer clear before idling (halt, mwait) */ -DEFINE_STATIC_KEY_FALSE(mds_idle_clear); -EXPORT_SYMBOL_GPL(mds_idle_clear); +/* Control CPU buffer clear before idling (halt, mwait) */ +DEFINE_STATIC_KEY_FALSE(cpu_buf_idle_clear); +EXPORT_SYMBOL_GPL(cpu_buf_idle_clear);
/* Controls CPU Fill buffer clear before KVM guest MMIO accesses */ DEFINE_STATIC_KEY_FALSE(mmio_stale_data_clear); @@ -445,7 +445,7 @@ static void __init mmio_select_mitigatio * is required irrespective of SMT state. */ if (!(ia32_cap & ARCH_CAP_FBSDP_NO)) - static_branch_enable(&mds_idle_clear); + static_branch_enable(&cpu_buf_idle_clear);
/* * Check if the system has the right microcode. @@ -1922,10 +1922,10 @@ static void update_mds_branch_idle(void) return;
if (sched_smt_active()) { - static_branch_enable(&mds_idle_clear); + static_branch_enable(&cpu_buf_idle_clear); } else if (mmio_mitigation == MMIO_MITIGATION_OFF || (ia32_cap & ARCH_CAP_FBSDP_NO)) { - static_branch_disable(&mds_idle_clear); + static_branch_disable(&cpu_buf_idle_clear); } }
--- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6810,7 +6810,7 @@ static noinstr void vmx_vcpu_enter_exit( vmx_l1d_flush(vcpu); else if (static_branch_unlikely(&mmio_stale_data_clear) && kvm_arch_has_assigned_device(vcpu->kvm)) - mds_clear_cpu_buffers(); + x86_clear_cpu_buffers();
vmx_disable_fb_clear(vmx);