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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

...0x0f, 0x01, 0xf8 }, // swapgs .mov64 = { 0x48, 0x89, 0xf8 }, // mov %rdi, %rax -# else - .mmu_write_cr3 = { 0x0f, 0x22, 0xd8 }, // mov %eax, %cr3 - .irq_restore_fl = { 0x50, 0x9d }, // push %eax; popf - .cpu_iret = { 0xcf }, // iret -# endif }; unsigned int paravirt_patch_ident_64(void *insn_buff, unsigned int len) { -#ifdef CONFIG_X86_64 return PATCH(xxl, mov64, insn_buff, len); -#endif - return 0; } # endif /* CONFIG_PARAVIRT_XXL */ @@ -98,13 +85,9 @@ unsigned int native_patch(u8 type, void *insn_buff, unsigned long addr, PATCH_CASE(mmu, read_cr3, xxl, insn_buff, len); PATCH_CA...

...0x0f, 0x01, 0xf8 }, // swapgs .mov64 = { 0x48, 0x89, 0xf8 }, // mov %rdi, %rax -# else - .mmu_write_cr3 = { 0x0f, 0x22, 0xd8 }, // mov %eax, %cr3 - .irq_restore_fl = { 0x50, 0x9d }, // push %eax; popf - .cpu_iret = { 0xcf }, // iret -# endif }; unsigned int paravirt_patch_ident_64(void *insn_buff, unsigned int len) { -#ifdef CONFIG_X86_64 return PATCH(xxl, mov64, insn_buff, len); -#endif - return 0; } # endif /* CONFIG_PARAVIRT_XXL */ @@ -98,13 +85,9 @@ unsigned int native_patch(u8 type, void *insn_buff, unsigned long addr, PATCH_CASE(mmu, read_cr3, xxl, insn_buff, len); PATCH_CA...

The long term plan has been to replace Xen PV guests by PVH. The first victim of that plan are now 32-bit PV guests, as those are used only rather seldom these days. Xen on x86 requires 64-bit support and with Grub2 now supporting PVH officially since version 2.04 there is no need to keep 32-bit PV guest support alive in the Linux kernel. Additionally Meltdown mitigation is not available in the

..._patch_default() warn: uncapped user index '*(&pv_ops + type)' arch/x86/kernel/paravirt.c:124 paravirt_patch_default() error: buffer overflow '&pv_ops' 90 <= 255 user_rl='0-255' arch/x86/kernel/paravirt.c 116 unsigned paravirt_patch_default(u8 type, void *insn_buff, 117 unsigned long addr, unsigned len) 118 { 119 /* 120 * Neat trick to map patch type back to the call within the 121 * corresponding structure. 122 */ 123 void *opfunc = *((void **)&pv_ops +...

The long term plan has been to replace Xen PV guests by PVH. The first victim of that plan are now 32-bit PV guests, as those are used only rather seldom these days. Xen on x86 requires 64-bit support and with Grub2 now supporting PVH officially since version 2.04 there is no need to keep 32-bit PV guest support alive in the Linux kernel. Additionally Meltdown mitigation is not available in the

The long term plan has been to replace Xen PV guests by PVH. The first victim of that plan are now 32-bit PV guests, as those are used only rather seldom these days. Xen on x86 requires 64-bit support and with Grub2 now supporting PVH officially since version 2.04 there is no need to keep 32-bit PV guest support alive in the Linux kernel. Additionally Meltdown mitigation is not available in the

A lot of cleanup after removal of 32-bit Xen PV guest support in paravirt code. Changes in V4: - dropped patches 1-3, as already committed - addressed comments to V3 - added new patches 5+6 Changes in V3: - addressed comments to V2 - split patch 1 into 2 patches - new patches 3 and 7 Changes in V2: - rebase to 5.8 kernel - addressed comments to V1 - new patches 3 and 4 Juergen Gross (6):

...id); +#endif #define paravirt_nop ((void *)_paravirt_nop) diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index 42e182868873..5ec2071570a4 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -64,11 +64,11 @@ static unsigned paravirt_patch_call(void *insn_buff, const void *target, } #ifdef CONFIG_PARAVIRT_XXL -/* identity function, which can be inlined */ -u64 notrace _paravirt_ident_64(u64 x) -{ - return x; -} +DEFINE_PARAVIRT_ASM(_paravirt_ident_64, "mov %rdi, %rax", .text); +DEFINE_PARAVIRT_ASM(pv_native_save_fl, "pushf; pop %rax&qu...

..._enabled.key); } if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index 98039d7fb998..ac00afed5570 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -159,6 +159,8 @@ unsigned paravirt_patch_insns(void *insn_buff, unsigned len, return insn_len; } +DEFINE_STATIC_KEY_TRUE(flush_tlb_multi_enabled); + static void native_flush_tlb(void) { __native_flush_tlb(); @@ -363,6 +365,7 @@ struct paravirt_patch_template pv_ops = { .mmu.flush_tlb_user = native_flush_tlb, .mmu.flush_tlb_kernel = native_flush_tl...

..._enabled.key); } if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index 98039d7fb998..ac00afed5570 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -159,6 +159,8 @@ unsigned paravirt_patch_insns(void *insn_buff, unsigned len, return insn_len; } +DEFINE_STATIC_KEY_TRUE(flush_tlb_multi_enabled); + static void native_flush_tlb(void) { __native_flush_tlb(); @@ -363,6 +365,7 @@ struct paravirt_patch_template pv_ops = { .mmu.flush_tlb_user = native_flush_tlb, .mmu.flush_tlb_kernel = native_flush_tl...

...id); +#endif #define paravirt_nop ((void *)_paravirt_nop) diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index 42e182868873..d25ac4b08c41 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -64,11 +64,11 @@ static unsigned paravirt_patch_call(void *insn_buff, const void *target, } #ifdef CONFIG_PARAVIRT_XXL -/* identity function, which can be inlined */ -u64 notrace _paravirt_ident_64(u64 x) -{ - return x; -} +DEFINE_PARAVIRT_ASM(_paravirt_ident_64, "mov %rdi, %rax", .text); +DEFINE_PARAVIRT_ASM(pv_native_save_fl, "pushf; pop %rax&qu...

...(kvm_para_has_feature(KVM_FEATURE_PV_EOI)) > diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c > index 98039d7fb998..ac00afed5570 100644 > --- a/arch/x86/kernel/paravirt.c > +++ b/arch/x86/kernel/paravirt.c > @@ -159,6 +159,8 @@ unsigned paravirt_patch_insns(void *insn_buff, unsigned len, > return insn_len; > } > > +DEFINE_STATIC_KEY_TRUE(flush_tlb_multi_enabled); > + > static void native_flush_tlb(void) > { > __native_flush_tlb(); > @@ -363,6 +365,7 @@ struct paravirt_patch_template pv_ops = { > .mmu.flush_tlb_user = native_fl...

...re(KVM_FEATURE_PV_EOI)) >> diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c >> index 98039d7fb998..ac00afed5570 100644 >> --- a/arch/x86/kernel/paravirt.c >> +++ b/arch/x86/kernel/paravirt.c >> @@ -159,6 +159,8 @@ unsigned paravirt_patch_insns(void *insn_buff, unsigned len, >> return insn_len; >> } >> >> +DEFINE_STATIC_KEY_TRUE(flush_tlb_multi_enabled); >> + >> static void native_flush_tlb(void) >> { >> __native_flush_tlb(); >> @@ -363,6 +365,7 @@ struct paravirt_patch_template pv_ops = { >>...

...re(KVM_FEATURE_PV_EOI)) >> diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c >> index 98039d7fb998..ac00afed5570 100644 >> --- a/arch/x86/kernel/paravirt.c >> +++ b/arch/x86/kernel/paravirt.c >> @@ -159,6 +159,8 @@ unsigned paravirt_patch_insns(void *insn_buff, unsigned len, >> return insn_len; >> } >> >> +DEFINE_STATIC_KEY_TRUE(flush_tlb_multi_enabled); >> + >> static void native_flush_tlb(void) >> { >> __native_flush_tlb(); >> @@ -363,6 +365,7 @@ struct paravirt_patch_template pv_ops = { >>...

..._enabled.key); } if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index 5492a669f658..1314f89304a8 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -171,6 +171,8 @@ unsigned paravirt_patch_insns(void *insn_buff, unsigned len, return insn_len; } +DEFINE_STATIC_KEY_TRUE(flush_tlb_multi_enabled); + static void native_flush_tlb(void) { __native_flush_tlb(); @@ -375,6 +377,7 @@ struct paravirt_patch_template pv_ops = { .mmu.flush_tlb_user = native_flush_tlb, .mmu.flush_tlb_kernel = native_flush_tl...

..._enabled.key); } if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index 5492a669f658..1314f89304a8 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -171,6 +171,8 @@ unsigned paravirt_patch_insns(void *insn_buff, unsigned len, return insn_len; } +DEFINE_STATIC_KEY_TRUE(flush_tlb_multi_enabled); + static void native_flush_tlb(void) { __native_flush_tlb(); @@ -375,6 +377,7 @@ struct paravirt_patch_template pv_ops = { .mmu.flush_tlb_user = native_flush_tlb, .mmu.flush_tlb_kernel = native_flush_tl...

..._enabled.key); } if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index 5492a669f658..1314f89304a8 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -171,6 +171,8 @@ unsigned paravirt_patch_insns(void *insn_buff, unsigned len, return insn_len; } +DEFINE_STATIC_KEY_TRUE(flush_tlb_multi_enabled); + static void native_flush_tlb(void) { __native_flush_tlb(); @@ -375,6 +377,7 @@ struct paravirt_patch_template pv_ops = { .mmu.flush_tlb_user = native_flush_tlb, .mmu.flush_tlb_kernel = native_flush_tl...

..._enabled.key); } if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index 5492a669f658..1314f89304a8 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -171,6 +171,8 @@ unsigned paravirt_patch_insns(void *insn_buff, unsigned len, return insn_len; } +DEFINE_STATIC_KEY_TRUE(flush_tlb_multi_enabled); + static void native_flush_tlb(void) { __native_flush_tlb(); @@ -375,6 +377,7 @@ struct paravirt_patch_template pv_ops = { .mmu.flush_tlb_user = native_flush_tlb, .mmu.flush_tlb_kernel = native_flush_tl...