search for: _paravirt_ident_64

?ukasz Daniluk reported that on a RHEL kernel that his machine would lock up after enabling function tracer. I asked him to bisect the functions within available_filter_functions, which he did and it came down to three: _paravirt_nop(), _paravirt_ident_32() and _paravirt_ident_64() It was found that this is only an issue when noreplace-paravirt is added to the kernel command line. This means that those functions are most likely called within critical sections of the funtion tracer, and must not be traced. In newer kenels _paravirt_nop() is defined within gcc asm(), and i...

?ukasz Daniluk reported that on a RHEL kernel that his machine would lock up after enabling function tracer. I asked him to bisect the functions within available_filter_functions, which he did and it came down to three: _paravirt_nop(), _paravirt_ident_32() and _paravirt_ident_64() It was found that this is only an issue when noreplace-paravirt is added to the kernel command line. This means that those functions are most likely called within critical sections of the funtion tracer, and must not be traced. In newer kenels _paravirt_nop() is defined within gcc asm(), and i...

...ravirt_types.h b/arch/x86/include/asm/paravirt_types.h index 8c1da419260f..49f5c6955229 100644 --- a/arch/x86/include/asm/paravirt_types.h +++ b/arch/x86/include/asm/paravirt_types.h @@ -562,8 +562,14 @@ void paravirt_flush_lazy_mmu(void); void _paravirt_nop(void); void paravirt_BUG(void); -u64 _paravirt_ident_64(u64); unsigned long paravirt_ret0(void); +#ifdef CONFIG_PARAVIRT_XXL +u64 _paravirt_ident_64(u64); +unsigned long pv_native_save_fl(void); +void pv_native_irq_disable(void); +void pv_native_irq_enable(void); +unsigned long pv_native_read_cr2(void); +#endif #define paravirt_nop ((void *)_paravir...

...t; wrote: > ?ukasz Daniluk reported that on a RHEL kernel that his machine would lock up > after enabling function tracer. I asked him to bisect the functions within > available_filter_functions, which he did and it came down to three: > > _paravirt_nop(), _paravirt_ident_32() and _paravirt_ident_64() > > It was found that this is only an issue when noreplace-paravirt is added to > the kernel command line. > > This means that those functions are most likely called within critical > sections of the funtion tracer, and must not be traced. > > In newer kenels _paravirt_...

...ravirt_types.h b/arch/x86/include/asm/paravirt_types.h index 8c1da419260f..49f5c6955229 100644 --- a/arch/x86/include/asm/paravirt_types.h +++ b/arch/x86/include/asm/paravirt_types.h @@ -562,8 +562,14 @@ void paravirt_flush_lazy_mmu(void); void _paravirt_nop(void); void paravirt_BUG(void); -u64 _paravirt_ident_64(u64); unsigned long paravirt_ret0(void); +#ifdef CONFIG_PARAVIRT_XXL +u64 _paravirt_ident_64(u64); +unsigned long pv_native_save_fl(void); +void pv_native_irq_disable(void); +void pv_native_irq_enable(void); +unsigned long pv_native_read_cr2(void); +#endif #define paravirt_nop ((void *)_paravir...

..._PREFIX_HERE, "", PVOP_CALL_ARG1(arg1)) #define PVOP_CALLEE1(rettype, op, arg1) \ __PVOP_CALLEESAVE(rettype, op, "", "", PVOP_CALL_ARG1(arg1)) @@ -690,6 +698,9 @@ void paravirt_flush_lazy_mmu(void); void _paravirt_nop(void); u32 _paravirt_ident_32(u32); u64 _paravirt_ident_64(u64); +#ifdef CONFIG_PARAVIRT_SPINLOCKS +void _paravirt_native_ticket_unlock(arch_spinlock_t *lock); +#endif #define paravirt_nop ((void *)_paravirt_nop) diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h index ab76c3e..40a1091 100644 --- a/arch/x86/include/asm/spin...

This is a small series getting rid of paravirt patching by switching completely to alternative patching for the same functionality. The basic idea is to add the capability to switch from indirect to direct calls via a special alternative patching option. This removes _some_ of the paravirt macro maze, but most of it needs to stay due to the need of hiding the call instructions from the compiler

This is a small series getting rid of paravirt patching by switching completely to alternative patching for the same functionality. The basic idea is to add the capability to switch from indirect to direct calls via a special alternative patching option. This removes _some_ of the paravirt macro maze, but most of it needs to stay due to the need of hiding the call instructions from the compiler

With virt_spin_lock() being a pvops function the bare metal case can be optimized by patching the call away completely. In case a kernel running as a guest it can decide whether to use paravitualized spinlocks, the current fallback to the unfair test-and-set scheme, or to mimic the bare metal behavior. Juergen Gross (4): paravirt: add generic _paravirt_false() function paravirt: switch

With virt_spin_lock() being a pvops function the bare metal case can be optimized by patching the call away completely. In case a kernel running as a guest it can decide whether to use paravitualized spinlocks, the current fallback to the unfair test-and-set scheme, or to mimic the bare metal behavior. Juergen Gross (4): paravirt: add generic _paravirt_false() function paravirt: switch

...post \ : call_clbr, ASM_CALL_CONSTRAINT \ - : paravirt_type(op), \ - paravirt_clobber(clbr), \ + : PV_INPUT_CONSTRAINTS(op, clbr), \ ##__VA_ARGS__ \ : "memory", "cc" extra_clbr); \ }) @@ -671,7 +675,7 @@ u64 _paravirt_ident_64(u64); /* These all sit in the .parainstructions section to tell us what to patch. */ struct paravirt_patch_site { - u8 *instr; /* original instructions */ + u8 *instr; /* original instructions */ u8 instrtype; /* type of this instruction */ u8 len; /* length of original instruction */...

Paravirtualized spinlocks produce some overhead even if the kernel is running on bare metal. The main reason are the more complex locking and unlocking functions. Especially unlocking is no longer just one instruction but so complex that it is no longer inlined. This patch series addresses this issue by adding two more pvops functions to reduce the size of the inlined spinlock functions. When

Paravirtualized spinlocks produce some overhead even if the kernel is running on bare metal. The main reason are the more complex locking and unlocking functions. Especially unlocking is no longer just one instruction but so complex that it is no longer inlined. This patch series addresses this issue by adding two more pvops functions to reduce the size of the inlined spinlock functions. When

Paravirt ops is currently only capable of either replacing a lot of Linux internal code or none at all. The are users that don't need all of the possibilities pv-ops delivers though. On KVM for example we're perfectly fine not using the PV MMU, thus not touching any MMU code. That way we don't have to improve pv-ops to become fast, we just don't compile the MMU parts in! This

Paravirt ops is currently only capable of either replacing a lot of Linux internal code or none at all. The are users that don't need all of the possibilities pv-ops delivers though. On KVM for example we're perfectly fine not using the PV MMU, thus not touching any MMU code. That way we don't have to improve pv-ops to become fast, we just don't compile the MMU parts in! This

Today paravirtualization is a all-or-nothing game: either a kernel is compiled with no paravirtualization support at all, or it is supporting paravirtualized environments like Xen pv-guests or lguest additionally to some paravirtualized tuning for KVM, Hyperv, VMWare or Xen HVM-guests. As support of pv-guests requires quite intrusive pv-hooks (e.g. all access functions to page table entries,

Today paravirtualization is a all-or-nothing game: either a kernel is compiled with no paravirtualization support at all, or it is supporting paravirtualized environments like Xen pv-guests or lguest additionally to some paravirtualized tuning for KVM, Hyperv, VMWare or Xen HVM-guests. As support of pv-guests requires quite intrusive pv-hooks (e.g. all access functions to page table entries,

..._debugreg); -NOKPROBE_SYMBOL(native_load_idt); - #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_PAE) /* 32-bit pagetable entries */ #define PTE_IDENT __PV_IS_CALLEE_SAVE(_paravirt_ident_32) @@ -394,84 +308,162 @@ NOKPROBE_SYMBOL(native_load_idt); #define PTE_IDENT __PV_IS_CALLEE_SAVE(_paravirt_ident_64) #endif -struct pv_mmu_ops pv_mmu_ops __ro_after_init = { - - .read_cr2 = native_read_cr2, - .write_cr2 = native_write_cr2, - .read_cr3 = __native_read_cr3, - .write_cr3 = native_write_cr3, - - .flush_tlb_user = native_flush_tlb, - .flush_tlb_kernel = native_flush_tlb_global, - .flush_tlb_one_us...

This series removes some no longer needed stuff from paravirt infrastructure and puts large quantities of paravirt ops under a new config option PARAVIRT_XXL which is selected by XEN_PV only. A pvops kernel without XEN_PV being configured is about 2.5% smaller with this series applied. tip commit 5800dc5c19f34e6e03b5adab1282535cb102fafd ("x86/paravirt: Fix spectre-v2 mitigations for

This series removes some no longer needed stuff from paravirt infrastructure and puts large quantities of paravirt ops under a new config option PARAVIRT_XXL which is selected by XEN_PV only. A pvops kernel without XEN_PV being configured is about 2.5% smaller with this series applied. tip commit 5800dc5c19f34e6e03b5adab1282535cb102fafd ("x86/paravirt: Fix spectre-v2 mitigations for