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Date:	Mon, 16 May 2016 11:18:03 +0100 (BST)
From:	Stefano Stabellini <sstabellini@...nel.org>
To:	Matt Fleming <matt@...eblueprint.co.uk>
cc:	Shannon Zhao <zhaoshenglong@...wei.com>,
	linux-arm-kernel@...ts.infradead.org, sstabellini@...nel.org,
	xen-devel@...ts.xen.org, linux-efi@...r.kernel.org,
	linux-kernel@...r.kernel.org, shannon.zhao@...aro.org,
	peter.huangpeng@...wei.com,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v2] Xen: EFI: Parse DT parameters for Xen specific UEFI

On Fri, 13 May 2016, Matt Fleming wrote:
> (Including more folks, quoting entire patch)
> 
> On Thu, 12 May, at 08:19:54PM, Shannon Zhao wrote:
> > From: Shannon Zhao <shannon.zhao@...aro.org>
> > 
> > The EFI DT parameters for bare metal are located under /chosen node,
> > while for Xen Dom0 they are located under /hyperviosr/uefi node. These
> > parameters under /chosen and /hyperviosr/uefi are not expected to appear
> > at the same time.
> > Parse these EFI parameters and initialize EFI like the way for bare
> > metal except the runtime services because the runtime services for Xen
> > Dom0 are available through hypercalls and they are always enabled. So it
> > sets the EFI_RUNTIME_SERVICES flag if it finds /hyperviosr/uefi node and
> > bails out in arm_enable_runtime_services() when EFI_RUNTIME_SERVICES
> > flag is set already.
> > 
> > CC: Matt Fleming <matt@...eblueprint.co.uk>
> > Signed-off-by: Shannon Zhao <shannon.zhao@...aro.org>
> > ---
> > v2: rebase it on top of EFI and Xen next branch, add some comments to
> > explain the codes. 
> > ---
> >  arch/arm/xen/enlighten.c           | 22 +++++++++++
> >  drivers/firmware/efi/arm-runtime.c |  5 +++
> >  drivers/firmware/efi/efi.c         | 81 ++++++++++++++++++++++++++++++--------
> >  3 files changed, 92 insertions(+), 16 deletions(-)
>  
> This looks good to me. Thanks for all the work Shannon.
> 
> Stefan, OK, let's figure out how to deal with this.
> 
> What I've done is merge xen/linux-next into the 'efi/xen-arm' topic
> branch and applied this patch here,
> 
>   https://git.kernel.org/cgit/linux/kernel/git/mfleming/efi.git/log/?h=efi/arm-xen
> 
> Yes, the merge includes some Xen patches that are not actually needed
> for any of the EFI patches, but Linus has complained about picking
> random commits of a tree to merge. At least this way this is all the
> Xen linux-next material.
> 
> If you're OK with this, and assuming no one else has any preferred
> methods, I'll send out a pull request to tip over the weekend.

I am OK with it. Thanks!


> > diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
> > index 13e3e9f..d4f36eb 100644
> > --- a/arch/arm/xen/enlighten.c
> > +++ b/arch/arm/xen/enlighten.c
> > @@ -15,7 +15,9 @@
> >  #include <asm/paravirt.h>
> >  #include <asm/xen/hypervisor.h>
> >  #include <asm/xen/hypercall.h>
> > +#include <asm/xen/xen-ops.h>
> >  #include <asm/system_misc.h>
> > +#include <asm/efi.h>
> >  #include <linux/interrupt.h>
> >  #include <linux/irqreturn.h>
> >  #include <linux/module.h>
> > @@ -261,6 +263,19 @@ static int __init fdt_find_hyper_node(unsigned long node, const char *uname,
> >  	    !strncmp(hyper_node.prefix, s, strlen(hyper_node.prefix)))
> >  		hyper_node.version = s + strlen(hyper_node.prefix);
> >  
> > +	/*
> > +	 * Check if Xen supports EFI by checking whether there is the
> > +	 * "/hypervisor/uefi" node in DT. If so, runtime services are available
> > +	 * through proxy functions (e.g. in case of Xen dom0 EFI implementation
> > +	 * they call special hypercall which executes relevant EFI functions)
> > +	 * and that is why they are always enabled.
> > +	 */
> > +	if (IS_ENABLED(CONFIG_XEN_EFI)) {
> > +		if ((of_get_flat_dt_subnode_by_name(node, "uefi") > 0) &&
> > +		    !efi_runtime_disabled())
> > +			set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
> > +	}
> > +
> >  	return 0;
> >  }
> >  
> > @@ -352,6 +367,13 @@ static int __init xen_guest_init(void)
> >  		return -ENODEV;
> >  	}
> >  
> > +	/*
> > +	 * The fdt parsing codes have set EFI_RUNTIME_SERVICES if Xen EFI
> > +	 * parameters are found. Force enable runtime services.
> > +	 */
> > +	if (efi_enabled(EFI_RUNTIME_SERVICES))
> > +		xen_efi_runtime_setup();
> > +
> >  	shared_info_page = (struct shared_info *)get_zeroed_page(GFP_KERNEL);
> >  
> >  	if (!shared_info_page) {
> > diff --git a/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c
> > index 17ccf0a..c394b81 100644
> > --- a/drivers/firmware/efi/arm-runtime.c
> > +++ b/drivers/firmware/efi/arm-runtime.c
> > @@ -107,6 +107,11 @@ static int __init arm_enable_runtime_services(void)
> >  		return 0;
> >  	}
> >  
> > +	if (efi_enabled(EFI_RUNTIME_SERVICES)) {
> > +		pr_info("EFI runtime services access via paravirt.\n");
> > +		return 0;
> > +	}
> > +
> >  	pr_info("Remapping and enabling EFI services.\n");
> >  
> >  	mapsize = efi.memmap.map_end - efi.memmap.map;
> > diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> > index 05509f3..1c6f9dd 100644
> > --- a/drivers/firmware/efi/efi.c
> > +++ b/drivers/firmware/efi/efi.c
> > @@ -472,12 +472,14 @@ device_initcall(efi_load_efivars);
> >  		FIELD_SIZEOF(struct efi_fdt_params, field) \
> >  	}
> >  
> > -static __initdata struct {
> > +struct params {
> >  	const char name[32];
> >  	const char propname[32];
> >  	int offset;
> >  	int size;
> > -} dt_params[] = {
> > +};
> > +
> > +static __initdata struct params fdt_params[] = {
> >  	UEFI_PARAM("System Table", "linux,uefi-system-table", system_table),
> >  	UEFI_PARAM("MemMap Address", "linux,uefi-mmap-start", mmap),
> >  	UEFI_PARAM("MemMap Size", "linux,uefi-mmap-size", mmap_size),
> > @@ -485,44 +487,91 @@ static __initdata struct {
> >  	UEFI_PARAM("MemMap Desc. Version", "linux,uefi-mmap-desc-ver", desc_ver)
> >  };
> >  
> > +static __initdata struct params xen_fdt_params[] = {
> > +	UEFI_PARAM("System Table", "xen,uefi-system-table", system_table),
> > +	UEFI_PARAM("MemMap Address", "xen,uefi-mmap-start", mmap),
> > +	UEFI_PARAM("MemMap Size", "xen,uefi-mmap-size", mmap_size),
> > +	UEFI_PARAM("MemMap Desc. Size", "xen,uefi-mmap-desc-size", desc_size),
> > +	UEFI_PARAM("MemMap Desc. Version", "xen,uefi-mmap-desc-ver", desc_ver)
> > +};
> > +
> > +#define EFI_FDT_PARAMS_SIZE	ARRAY_SIZE(fdt_params)
> > +
> > +static __initdata struct {
> > +	const char *uname;
> > +	const char *subnode;
> > +	struct params *params;
> > +} dt_params[] = {
> > +	{ "hypervisor", "uefi", xen_fdt_params },
> > +	{ "chosen", NULL, fdt_params },
> > +};
> > +
> >  struct param_info {
> >  	int found;
> >  	void *params;
> > +	const char *missing;
> >  };
> >  
> > -static int __init fdt_find_uefi_params(unsigned long node, const char *uname,
> > -				       int depth, void *data)
> > +static int __init __find_uefi_params(unsigned long node,
> > +				     struct param_info *info,
> > +				     struct params *params)
> >  {
> > -	struct param_info *info = data;
> >  	const void *prop;
> >  	void *dest;
> >  	u64 val;
> >  	int i, len;
> >  
> > -	if (depth != 1 || strcmp(uname, "chosen") != 0)
> > -		return 0;
> > -
> > -	for (i = 0; i < ARRAY_SIZE(dt_params); i++) {
> > -		prop = of_get_flat_dt_prop(node, dt_params[i].propname, &len);
> > -		if (!prop)
> > +	for (i = 0; i < EFI_FDT_PARAMS_SIZE; i++) {
> > +		prop = of_get_flat_dt_prop(node, params[i].propname, &len);
> > +		if (!prop) {
> > +			info->missing = params[i].name;
> >  			return 0;
> > -		dest = info->params + dt_params[i].offset;
> > +		}
> > +
> > +		dest = info->params + params[i].offset;
> >  		info->found++;
> >  
> >  		val = of_read_number(prop, len / sizeof(u32));
> >  
> > -		if (dt_params[i].size == sizeof(u32))
> > +		if (params[i].size == sizeof(u32))
> >  			*(u32 *)dest = val;
> >  		else
> >  			*(u64 *)dest = val;
> >  
> >  		if (efi_enabled(EFI_DBG))
> > -			pr_info("  %s: 0x%0*llx\n", dt_params[i].name,
> > -				dt_params[i].size * 2, val);
> > +			pr_info("  %s: 0x%0*llx\n", params[i].name,
> > +				params[i].size * 2, val);
> >  	}
> > +
> >  	return 1;
> >  }
> >  
> > +static int __init fdt_find_uefi_params(unsigned long node, const char *uname,
> > +				       int depth, void *data)
> > +{
> > +	struct param_info *info = data;
> > +	int i;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(dt_params); i++) {
> > +		const char *subnode = dt_params[i].subnode;
> > +
> > +		if (depth != 1 || strcmp(uname, dt_params[i].uname) != 0) {
> > +			info->missing = dt_params[i].params[0].name;
> > +			continue;
> > +		}
> > +
> > +		if (subnode) {
> > +			node = of_get_flat_dt_subnode_by_name(node, subnode);
> > +			if (node < 0)
> > +				return 0;
> > +		}
> > +
> > +		return __find_uefi_params(node, info, dt_params[i].params);
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> >  int __init efi_get_fdt_params(struct efi_fdt_params *params)
> >  {
> >  	struct param_info info;
> > @@ -538,7 +587,7 @@ int __init efi_get_fdt_params(struct efi_fdt_params *params)
> >  		pr_info("UEFI not found.\n");
> >  	else if (!ret)
> >  		pr_err("Can't find '%s' in device tree!\n",
> > -		       dt_params[info.found].name);
> > +		       info.missing);
> >  
> >  	return ret;
> >  }
> > -- 
> > 2.0.4
> > 
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-efi" in
> > the body of a message to majordomo@...r.kernel.org
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> 

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