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Message-ID: <87r1kxemsj.fsf@vitty.brq.redhat.com>
Date: Tue, 02 Mar 2021 13:57:00 +0100
From: Vitaly Kuznetsov <vkuznets@...hat.com>
To: Michael Kelley <mikelley@...rosoft.com>
Cc: mikelley@...rosoft.com, linux-kernel@...r.kernel.org,
x86@...nel.org, linux-arch@...r.kernel.org, sthemmin@...rosoft.com,
kys@...rosoft.com, wei.liu@...nel.org, tglx@...utronix.de,
mingo@...hat.com, bp@...en8.de, hpa@...or.com,
daniel.lezcano@...aro.org, arnd@...db.de,
linux-hyperv@...r.kernel.org
Subject: Re: ** POTENTIAL FRAUD ALERT - RED HAT ** [PATCH v2 01/10] Drivers:
hv: vmbus: Move Hyper-V page allocator to arch neutral code
Michael Kelley <mikelley@...rosoft.com> writes:
> The Hyper-V page allocator functions are implemented in an architecture
> neutral way. Move them into the architecture neutral VMbus module so
> a separate implementation for ARM64 is not needed.
>
> No functional change.
>
> Signed-off-by: Michael Kelley <mikelley@...rosoft.com>
> Reviewed-by: Boqun Feng <boqun.feng@...il.com>
> ---
> arch/x86/hyperv/hv_init.c | 22 ----------------------
> arch/x86/include/asm/mshyperv.h | 5 -----
> drivers/hv/hv.c | 36 ++++++++++++++++++++++++++++++++++++
> include/asm-generic/mshyperv.h | 4 ++++
> 4 files changed, 40 insertions(+), 27 deletions(-)
>
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index b81047d..4bdb344 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -54,28 +54,6 @@
> u32 hv_max_vp_index;
> EXPORT_SYMBOL_GPL(hv_max_vp_index);
>
> -void *hv_alloc_hyperv_page(void)
> -{
> - BUILD_BUG_ON(PAGE_SIZE != HV_HYP_PAGE_SIZE);
> -
> - return (void *)__get_free_page(GFP_KERNEL);
> -}
> -EXPORT_SYMBOL_GPL(hv_alloc_hyperv_page);
> -
> -void *hv_alloc_hyperv_zeroed_page(void)
> -{
> - BUILD_BUG_ON(PAGE_SIZE != HV_HYP_PAGE_SIZE);
> -
> - return (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
> -}
> -EXPORT_SYMBOL_GPL(hv_alloc_hyperv_zeroed_page);
> -
> -void hv_free_hyperv_page(unsigned long addr)
> -{
> - free_page(addr);
> -}
> -EXPORT_SYMBOL_GPL(hv_free_hyperv_page);
> -
> static int hv_cpu_init(unsigned int cpu)
> {
> u64 msr_vp_index;
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index ccf60a8..ef6e968 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -233,9 +233,6 @@ static inline struct hv_vp_assist_page *hv_get_vp_assist_page(unsigned int cpu)
>
> void __init hyperv_init(void);
> void hyperv_setup_mmu_ops(void);
> -void *hv_alloc_hyperv_page(void);
> -void *hv_alloc_hyperv_zeroed_page(void);
> -void hv_free_hyperv_page(unsigned long addr);
> void set_hv_tscchange_cb(void (*cb)(void));
> void clear_hv_tscchange_cb(void);
> void hyperv_stop_tsc_emulation(void);
> @@ -272,8 +269,6 @@ int hv_map_ioapic_interrupt(int ioapic_id, bool level, int vcpu, int vector,
> #else /* CONFIG_HYPERV */
> static inline void hyperv_init(void) {}
> static inline void hyperv_setup_mmu_ops(void) {}
> -static inline void *hv_alloc_hyperv_page(void) { return NULL; }
> -static inline void hv_free_hyperv_page(unsigned long addr) {}
> static inline void set_hv_tscchange_cb(void (*cb)(void)) {}
> static inline void clear_hv_tscchange_cb(void) {}
> static inline void hyperv_stop_tsc_emulation(void) {};
> diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
> index f202ac7..cca8d5e 100644
> --- a/drivers/hv/hv.c
> +++ b/drivers/hv/hv.c
> @@ -37,6 +37,42 @@ int hv_init(void)
> }
>
> /*
> + * Functions for allocating and freeing memory with size and
> + * alignment HV_HYP_PAGE_SIZE. These functions are needed because
> + * the guest page size may not be the same as the Hyper-V page
> + * size. We depend upon kmalloc() aligning power-of-two size
> + * allocations to the allocation size boundary, so that the
> + * allocated memory appears to Hyper-V as a page of the size
> + * it expects.
> + */
> +
> +void *hv_alloc_hyperv_page(void)
> +{
> + BUILD_BUG_ON(PAGE_SIZE < HV_HYP_PAGE_SIZE);
> +
> + if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
> + return (void *)__get_free_page(GFP_KERNEL);
> + else
> + return kmalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
PAGE_SIZE and HV_HYP_PAGE_SIZE are known compile-time and in case this
won't change in the future we can probably write this as
#if PAGE_SIZE == HV_HYP_PAGE_SIZE
return (void *)__get_free_page(GFP_KERNEL);
#else
return kmalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
#endif
(not sure if the output is going to be any different with e.g. gcc's '-O2')
> +}
> +
> +void *hv_alloc_hyperv_zeroed_page(void)
> +{
> + if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
> + return (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
> + else
> + return kzalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
> +}
> +
> +void hv_free_hyperv_page(unsigned long addr)
> +{
> + if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
> + free_page(addr);
> + else
> + kfree((void *)addr);
> +}
> +
> +/*
> * hv_post_message - Post a message using the hypervisor message IPC.
> *
> * This involves a hypercall.
> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
> index dff58a3..694b5bc 100644
> --- a/include/asm-generic/mshyperv.h
> +++ b/include/asm-generic/mshyperv.h
> @@ -117,6 +117,10 @@ static inline void vmbus_signal_eom(struct hv_message *msg, u32 old_msg_type)
> /* Sentinel value for an uninitialized entry in hv_vp_index array */
> #define VP_INVAL U32_MAX
>
> +void *hv_alloc_hyperv_page(void);
> +void *hv_alloc_hyperv_zeroed_page(void);
> +void hv_free_hyperv_page(unsigned long addr);
> +
> /**
> * hv_cpu_number_to_vp_number() - Map CPU to VP.
> * @cpu_number: CPU number in Linux terms
--
Vitaly
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