linux-kernel - Re: [PATCH] x86/ioperm: add new paravirt function update_io

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Date:   Fri, 28 Feb 2020 16:35:50 +0100
From:   Jürgen Groß <jgross@...e.com>
To:     xen-devel@...ts.xenproject.org, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Hellstrom <thellstrom@...are.com>,
        "VMware, Inc." <pv-drivers@...are.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        stable@...r.kernel.org
Subject: Re: [PATCH] x86/ioperm: add new paravirt function update_io_bitmap

Friendly ping...

On 18.02.20 16:47, Juergen Gross wrote:
> Commit 111e7b15cf10f6 ("x86/ioperm: Extend IOPL config to control
> ioperm() as well") reworked the iopl syscall to use I/O bitmaps.
> 
> Unfortunately this broke Xen PV domains using that syscall as there
> is currently no I/O bitmap support in PV domains.
> 
> Add I/O bitmap support via a new paravirt function update_io_bitmap
> which Xen PV domains can use to update their I/O bitmaps via a
> hypercall.
> 
> Fixes: 111e7b15cf10f6 ("x86/ioperm: Extend IOPL config to control ioperm() as well")
> Reported-by: Jan Beulich <jbeulich@...e.com>
> Cc: <stable@...r.kernel.org> # 5.5
> Signed-off-by: Juergen Gross <jgross@...e.com>
> Reviewed-by: Jan Beulich <jbeulich@...e.com>
> Tested-by: Jan Beulich <jbeulich@...e.com>
> ---
>   arch/x86/include/asm/io_bitmap.h      |  9 ++++++++-
>   arch/x86/include/asm/paravirt.h       |  7 +++++++
>   arch/x86/include/asm/paravirt_types.h |  4 ++++
>   arch/x86/kernel/paravirt.c            |  5 +++++
>   arch/x86/kernel/process.c             |  2 +-
>   arch/x86/xen/enlighten_pv.c           | 25 +++++++++++++++++++++++++
>   6 files changed, 50 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/include/asm/io_bitmap.h b/arch/x86/include/asm/io_bitmap.h
> index 02c6ef8f7667..07344d82e88e 100644
> --- a/arch/x86/include/asm/io_bitmap.h
> +++ b/arch/x86/include/asm/io_bitmap.h
> @@ -19,7 +19,14 @@ struct task_struct;
>   void io_bitmap_share(struct task_struct *tsk);
>   void io_bitmap_exit(void);
>   
> -void tss_update_io_bitmap(void);
> +void native_tss_update_io_bitmap(void);
> +
> +#ifdef CONFIG_PARAVIRT_XXL
> +#include <asm/paravirt.h>
> +#else
> +#define tss_update_io_bitmap native_tss_update_io_bitmap
> +#endif
> +
>   #else
>   static inline void io_bitmap_share(struct task_struct *tsk) { }
>   static inline void io_bitmap_exit(void) { }
> diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
> index 86e7317eb31f..694d8daf4983 100644
> --- a/arch/x86/include/asm/paravirt.h
> +++ b/arch/x86/include/asm/paravirt.h
> @@ -295,6 +295,13 @@ static inline void write_idt_entry(gate_desc *dt, int entry, const gate_desc *g)
>   	PVOP_VCALL3(cpu.write_idt_entry, dt, entry, g);
>   }
>   
> +#ifdef CONFIG_X86_IOPL_IOPERM
> +static inline void tss_update_io_bitmap(void)
> +{
> +	PVOP_VCALL0(cpu.update_io_bitmap);
> +}
> +#endif
> +
>   static inline void paravirt_activate_mm(struct mm_struct *prev,
>   					struct mm_struct *next)
>   {
> diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
> index 84812964d3dd..732f62e04ddb 100644
> --- a/arch/x86/include/asm/paravirt_types.h
> +++ b/arch/x86/include/asm/paravirt_types.h
> @@ -140,6 +140,10 @@ struct pv_cpu_ops {
>   
>   	void (*load_sp0)(unsigned long sp0);
>   
> +#ifdef CONFIG_X86_IOPL_IOPERM
> +	void (*update_io_bitmap)(void);
> +#endif
> +
>   	void (*wbinvd)(void);
>   
>   	/* cpuid emulation, mostly so that caps bits can be disabled */
> diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
> index 789f5e4f89de..c131ba4e70ef 100644
> --- a/arch/x86/kernel/paravirt.c
> +++ b/arch/x86/kernel/paravirt.c
> @@ -30,6 +30,7 @@
>   #include <asm/timer.h>
>   #include <asm/special_insns.h>
>   #include <asm/tlb.h>
> +#include <asm/io_bitmap.h>
>   
>   /*
>    * nop stub, which must not clobber anything *including the stack* to
> @@ -341,6 +342,10 @@ struct paravirt_patch_template pv_ops = {
>   	.cpu.iret		= native_iret,
>   	.cpu.swapgs		= native_swapgs,
>   
> +#ifdef CONFIG_X86_IOPL_IOPERM
> +	.cpu.update_io_bitmap	= native_tss_update_io_bitmap,
> +#endif
> +
>   	.cpu.start_context_switch	= paravirt_nop,
>   	.cpu.end_context_switch		= paravirt_nop,
>   
> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
> index 839b5244e3b7..3053c85e0e42 100644
> --- a/arch/x86/kernel/process.c
> +++ b/arch/x86/kernel/process.c
> @@ -374,7 +374,7 @@ static void tss_copy_io_bitmap(struct tss_struct *tss, struct io_bitmap *iobm)
>   /**
>    * tss_update_io_bitmap - Update I/O bitmap before exiting to usermode
>    */
> -void tss_update_io_bitmap(void)
> +void native_tss_update_io_bitmap(void)
>   {
>   	struct tss_struct *tss = this_cpu_ptr(&cpu_tss_rw);
>   	struct thread_struct *t = &current->thread;
> diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
> index 1f756ffffe8b..feaf2e68ee5c 100644
> --- a/arch/x86/xen/enlighten_pv.c
> +++ b/arch/x86/xen/enlighten_pv.c
> @@ -72,6 +72,9 @@
>   #include <asm/mwait.h>
>   #include <asm/pci_x86.h>
>   #include <asm/cpu.h>
> +#ifdef CONFIG_X86_IOPL_IOPERM
> +#include <asm/io_bitmap.h>
> +#endif
>   
>   #ifdef CONFIG_ACPI
>   #include <linux/acpi.h>
> @@ -837,6 +840,25 @@ static void xen_load_sp0(unsigned long sp0)
>   	this_cpu_write(cpu_tss_rw.x86_tss.sp0, sp0);
>   }
>   
> +#ifdef CONFIG_X86_IOPL_IOPERM
> +static void xen_update_io_bitmap(void)
> +{
> +	struct physdev_set_iobitmap iobitmap;
> +	struct tss_struct *tss = this_cpu_ptr(&cpu_tss_rw);
> +
> +	native_tss_update_io_bitmap();
> +
> +	iobitmap.bitmap = (uint8_t *)(&tss->x86_tss) +
> +			  tss->x86_tss.io_bitmap_base;
> +	if (tss->x86_tss.io_bitmap_base == IO_BITMAP_OFFSET_INVALID)
> +		iobitmap.nr_ports = 0;
> +	else
> +		iobitmap.nr_ports = IO_BITMAP_BITS;
> +
> +	HYPERVISOR_physdev_op(PHYSDEVOP_set_iobitmap, &iobitmap);
> +}
> +#endif
> +
>   static void xen_io_delay(void)
>   {
>   }
> @@ -1046,6 +1068,9 @@ static const struct pv_cpu_ops xen_cpu_ops __initconst = {
>   	.write_idt_entry = xen_write_idt_entry,
>   	.load_sp0 = xen_load_sp0,
>   
> +#ifdef CONFIG_X86_IOPL_IOPERM
> +	.update_io_bitmap = xen_update_io_bitmap,
> +#endif
>   	.io_delay = xen_io_delay,
>   
>   	/* Xen takes care of %gs when switching to usermode for us */
>