From c9ae1b10d9561012a222e05f0d3ab4e93d301f06 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Tue, 7 Feb 2023 08:59:02 +0100 Subject: [PATCH 1/2] x86/paravirt: Merge activate_mm() and dup_mmap() callbacks The two paravirt callbacks .mmu.activate_mm() and .mmu.dup_mmap() are sharing the same implementations in all cases: for Xen PV guests they are pinning the PGD of the new mm_struct, and for all other cases they are a NOP. In the end, both callbacks are meant to register an address space with the underlying hypervisor, so there needs to be only a single callback for that purpose. So merge them to a common callback .mmu.enter_mmap() (in contrast to the corresponding already existing .mmu.exit_mmap()). As the first parameter of the old callbacks isn't used, drop it from the replacement one. [ bp: Remove last occurrence of paravirt_activate_mm() in asm/mmu_context.h ] Signed-off-by: Juergen Gross Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Boris Ostrovsky Reviewed-by: Srivatsa S. Bhat (VMware) Link: https://lore.kernel.org/r/20230207075902.7539-1-jgross@suse.com --- arch/x86/include/asm/mmu_context.h | 11 ++--------- arch/x86/include/asm/paravirt.h | 14 +++----------- arch/x86/include/asm/paravirt_types.h | 7 ++----- arch/x86/kernel/paravirt.c | 3 +-- arch/x86/mm/init.c | 2 +- arch/x86/xen/mmu_pv.c | 12 ++---------- 6 files changed, 11 insertions(+), 38 deletions(-) diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h index e01aa74a6de7..c3ad8a526378 100644 --- a/arch/x86/include/asm/mmu_context.h +++ b/arch/x86/include/asm/mmu_context.h @@ -16,13 +16,6 @@ extern atomic64_t last_mm_ctx_id; -#ifndef CONFIG_PARAVIRT_XXL -static inline void paravirt_activate_mm(struct mm_struct *prev, - struct mm_struct *next) -{ -} -#endif /* !CONFIG_PARAVIRT_XXL */ - #ifdef CONFIG_PERF_EVENTS DECLARE_STATIC_KEY_FALSE(rdpmc_never_available_key); DECLARE_STATIC_KEY_FALSE(rdpmc_always_available_key); @@ -135,7 +128,7 @@ extern void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, #define activate_mm(prev, next) \ do { \ - paravirt_activate_mm((prev), (next)); \ + paravirt_enter_mmap(next); \ switch_mm((prev), (next), NULL); \ } while (0); @@ -168,7 +161,7 @@ static inline void arch_dup_pkeys(struct mm_struct *oldmm, static inline int arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm) { arch_dup_pkeys(oldmm, mm); - paravirt_arch_dup_mmap(oldmm, mm); + paravirt_enter_mmap(mm); return ldt_dup_context(oldmm, mm); } diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h index cf40e813b3d7..b49778664d2b 100644 --- a/arch/x86/include/asm/paravirt.h +++ b/arch/x86/include/asm/paravirt.h @@ -334,16 +334,9 @@ static inline void tss_update_io_bitmap(void) } #endif -static inline void paravirt_activate_mm(struct mm_struct *prev, - struct mm_struct *next) +static inline void paravirt_enter_mmap(struct mm_struct *next) { - PVOP_VCALL2(mmu.activate_mm, prev, next); -} - -static inline void paravirt_arch_dup_mmap(struct mm_struct *oldmm, - struct mm_struct *mm) -{ - PVOP_VCALL2(mmu.dup_mmap, oldmm, mm); + PVOP_VCALL1(mmu.enter_mmap, next); } static inline int paravirt_pgd_alloc(struct mm_struct *mm) @@ -789,8 +782,7 @@ extern void default_banner(void); #ifndef __ASSEMBLY__ #ifndef CONFIG_PARAVIRT_XXL -static inline void paravirt_arch_dup_mmap(struct mm_struct *oldmm, - struct mm_struct *mm) +static inline void paravirt_enter_mmap(struct mm_struct *mm) { } #endif diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h index 8c1da419260f..71bf64b963df 100644 --- a/arch/x86/include/asm/paravirt_types.h +++ b/arch/x86/include/asm/paravirt_types.h @@ -164,11 +164,8 @@ struct pv_mmu_ops { unsigned long (*read_cr3)(void); void (*write_cr3)(unsigned long); - /* Hooks for intercepting the creation/use of an mm_struct. */ - void (*activate_mm)(struct mm_struct *prev, - struct mm_struct *next); - void (*dup_mmap)(struct mm_struct *oldmm, - struct mm_struct *mm); + /* Hook for intercepting the creation/use of an mm_struct. */ + void (*enter_mmap)(struct mm_struct *mm); /* Hooks for allocating and freeing a pagetable top-level */ int (*pgd_alloc)(struct mm_struct *mm); diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index 42e182868873..0e68a31be7c1 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -363,8 +363,7 @@ struct paravirt_patch_template pv_ops = { .mmu.make_pte = PTE_IDENT, .mmu.make_pgd = PTE_IDENT, - .mmu.dup_mmap = paravirt_nop, - .mmu.activate_mm = paravirt_nop, + .mmu.enter_mmap = paravirt_nop, .mmu.lazy_mode = { .enter = paravirt_nop, diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index cb258f58fdc8..cbc53da4c1b4 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -806,7 +806,7 @@ void __init poking_init(void) BUG_ON(!poking_mm); /* Xen PV guests need the PGD to be pinned. */ - paravirt_arch_dup_mmap(NULL, poking_mm); + paravirt_enter_mmap(poking_mm); /* * Randomize the poking address, but make sure that the following page diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c index ee29fb558f2e..b3b8d289b9ab 100644 --- a/arch/x86/xen/mmu_pv.c +++ b/arch/x86/xen/mmu_pv.c @@ -885,14 +885,7 @@ void xen_mm_unpin_all(void) spin_unlock(&pgd_lock); } -static void xen_activate_mm(struct mm_struct *prev, struct mm_struct *next) -{ - spin_lock(&next->page_table_lock); - xen_pgd_pin(next); - spin_unlock(&next->page_table_lock); -} - -static void xen_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm) +static void xen_enter_mmap(struct mm_struct *mm) { spin_lock(&mm->page_table_lock); xen_pgd_pin(mm); @@ -2153,8 +2146,7 @@ static const typeof(pv_ops) xen_mmu_ops __initconst = { .make_p4d = PV_CALLEE_SAVE(xen_make_p4d), #endif - .activate_mm = xen_activate_mm, - .dup_mmap = xen_dup_mmap, + .enter_mmap = xen_enter_mmap, .exit_mmap = xen_exit_mmap, .lazy_mode = { From 11af36cb898123fd4e0034f1bc6550aedcc87800 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Fri, 17 Mar 2023 07:33:25 +0100 Subject: [PATCH 2/2] x86/paravirt: Convert simple paravirt functions to asm All functions referenced via __PV_IS_CALLEE_SAVE() need to be assembler functions, as those functions calls are hidden from the compiler. In case the kernel is compiled with "-fzero-call-used-regs" the compiler will clobber caller-saved registers at the end of C functions, which will result in unexpectedly zeroed registers at the call site of the related paravirt functions. Replace the C functions with DEFINE_PARAVIRT_ASM() constructs using the same instructions as the related paravirt calls in the PVOP_ALT_[V]CALLEE*() macros. And since they're not C functions visible to the compiler anymore, latter won't do the callee-clobbered zeroing invoked by -fzero-call-used-regs and thus won't corrupt registers. [ bp: Extend commit message. ] Signed-off-by: Juergen Gross Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20230317063325.361-1-jgross@suse.com --- arch/x86/include/asm/paravirt_types.h | 8 +++++++- arch/x86/kernel/paravirt.c | 27 ++++++--------------------- 2 files changed, 13 insertions(+), 22 deletions(-) diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h index 71bf64b963df..4acbcddddc29 100644 --- a/arch/x86/include/asm/paravirt_types.h +++ b/arch/x86/include/asm/paravirt_types.h @@ -559,8 +559,14 @@ 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 *)_paravirt_nop) diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index 0e68a31be7c1..ac10b46c5832 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", .noinstr.text); +DEFINE_PARAVIRT_ASM(pv_native_irq_disable, "cli", .noinstr.text); +DEFINE_PARAVIRT_ASM(pv_native_irq_enable, "sti", .noinstr.text); +DEFINE_PARAVIRT_ASM(pv_native_read_cr2, "mov %cr2, %rax", .noinstr.text); #endif DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key); @@ -197,11 +197,6 @@ void paravirt_end_context_switch(struct task_struct *next) arch_enter_lazy_mmu_mode(); } -static noinstr unsigned long pv_native_read_cr2(void) -{ - return native_read_cr2(); -} - static noinstr void pv_native_write_cr2(unsigned long val) { native_write_cr2(val); @@ -222,16 +217,6 @@ noinstr void pv_native_wbinvd(void) native_wbinvd(); } -static noinstr void pv_native_irq_enable(void) -{ - native_irq_enable(); -} - -static noinstr void pv_native_irq_disable(void) -{ - native_irq_disable(); -} - static noinstr void pv_native_safe_halt(void) { native_safe_halt(); @@ -298,7 +283,7 @@ struct paravirt_patch_template pv_ops = { .cpu.end_context_switch = paravirt_nop, /* Irq ops. */ - .irq.save_fl = __PV_IS_CALLEE_SAVE(native_save_fl), + .irq.save_fl = __PV_IS_CALLEE_SAVE(pv_native_save_fl), .irq.irq_disable = __PV_IS_CALLEE_SAVE(pv_native_irq_disable), .irq.irq_enable = __PV_IS_CALLEE_SAVE(pv_native_irq_enable), .irq.safe_halt = pv_native_safe_halt,