[7/9] x86/hyperv: Initialize cpu and memory for SEV-SNP enlightened guest

  From: Tianyu Lan <tiala@microsoft.com>

Hyper-V enlightened guest doesn't have boot loader support.
Boot Linux kernel directly from hypervisor with data(kernel
image, initrd and parameter page) and memory for boot up that
is initialized via AMD SEV PSP proctol LAUNCH_UPDATE_DATA
(Please refernce https://www.amd.com/system/files/TechDocs/
55766_SEV-KM_API_Specification.pdf 1.3.1 Launch).

Kernel needs to read processor and memory info from EN_SEV_
SNP_PROCESSOR/MEM_INFO_ADDR address which are populated by Hyper-V.
Initialize smp cpu related ops, validate system memory and add
it into e820 table.

Signed-off-by: Tianyu Lan <tiala@microsoft.com>
---
 arch/x86/hyperv/ivm.c           | 93 +++++++++++++++++++++++++++++++++
 arch/x86/include/asm/mshyperv.h | 17 ++++++
 arch/x86/kernel/cpu/mshyperv.c  |  3 ++
 3 files changed, 113 insertions(+)
  

From: Tianyu Lan <ltykernel@gmail.com> Sent: Thursday, June 1, 2023 8:16 AM
> 
> Hyper-V enlightened guest doesn't have boot loader support.
> Boot Linux kernel directly from hypervisor with data(kernel

Add a space between "data" and "(kernel"

> image, initrd and parameter page) and memory for boot up that
> is initialized via AMD SEV PSP proctol LAUNCH_UPDATE_DATA

s/proctol/protocol/

> (Please refernce https://www.amd.com/system/files/TechDocs/55766_SEV-KM_API_Specification.pdf 1.3.1 Launch).

s/refernce/reference/

And the link above didn't work for me -- the "55766_SEV-KM_API_Specification.pdf"
part was separated from the rest of the URL, though it's possible the mangling
was done by Microsoft's email system.  Please double check that the URL is
correctly formatted with no spurious spaces.

Even better, maybe write this as:

Please reference Section 1.3.1 "Launch" of [1].

Then put the full link as [1] at the bottom of the commit message.

> 
> Kernel needs to read processor and memory info from EN_SEV_
> SNP_PROCESSOR/MEM_INFO_ADDR address which are populated by Hyper-V.
> Initialize smp cpu related ops, validate system memory and add
> it into e820 table.
> 
> Signed-off-by: Tianyu Lan <tiala@microsoft.com>
> ---
>  arch/x86/hyperv/ivm.c           | 93 +++++++++++++++++++++++++++++++++
>  arch/x86/include/asm/mshyperv.h | 17 ++++++
>  arch/x86/kernel/cpu/mshyperv.c  |  3 ++
>  3 files changed, 113 insertions(+)
> 
> diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
> index 5d3ee3124e00..e735507d0f54 100644
> --- a/arch/x86/hyperv/ivm.c
> +++ b/arch/x86/hyperv/ivm.c
> @@ -17,6 +17,11 @@
>  #include <asm/mem_encrypt.h>
>  #include <asm/mshyperv.h>
>  #include <asm/hypervisor.h>
> +#include <asm/coco.h>
> +#include <asm/io_apic.h>
> +#include <asm/sev.h>
> +#include <asm/realmode.h>
> +#include <asm/e820/api.h>
> 
>  #ifdef CONFIG_AMD_MEM_ENCRYPT
> 
> @@ -57,6 +62,8 @@ union hv_ghcb {
> 
>  static u16 hv_ghcb_version __ro_after_init;
> 
> +static u32 processor_count;
> +
>  u64 hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_size)
>  {
>  	union hv_ghcb *hv_ghcb;
> @@ -356,6 +363,92 @@ static bool hv_is_private_mmio(u64 addr)
>  	return false;
>  }
> 
> +static __init void hv_snp_get_smp_config(unsigned int early)
> +{
> +	/*
> +	 * The "early" is only to be true when there is AMD
> +	 * numa support. Hyper-V AMD SEV-SNP guest may not
> +	 * have numa support. To make sure smp config is
> +	 * always initialized, do that when early is false.
> +	 */
> +	if (early)
> +		return;
> +
> +	/*
> +	 * There is no firmware and ACPI MADT table support in
> +	 * in the Hyper-V SEV-SNP enlightened guest. Set smp
> +	 * related config variable here.
> +	 */
> +	while (num_processors < processor_count) {
> +		early_per_cpu(x86_cpu_to_apicid, num_processors) = num_processors;
> +		early_per_cpu(x86_bios_cpu_apicid, num_processors) = num_processors;
> +		physid_set(num_processors, phys_cpu_present_map);
> +		set_cpu_possible(num_processors, true);
> +		set_cpu_present(num_processors, true);
> +		num_processors++;
> +	}
> +}
> +
> +__init void hv_sev_init_mem_and_cpu(void)
> +{
> +	struct memory_map_entry *entry;
> +	struct e820_entry *e820_entry;
> +	u64 e820_end;
> +	u64 ram_end;
> +	u64 page;
> +
> +	/*
> +	 * Hyper-V enlightened snp guest boots kernel
> +	 * directly without bootloader. So roms, bios
> +	 * regions and reserve resources are not available.
> +	 * Set these callback to NULL.
> +	 */
> +	x86_platform.legacy.rtc			= 0;
> +	x86_platform.legacy.reserve_bios_regions = 0;
> +	x86_platform.set_wallclock		= set_rtc_noop;
> +	x86_platform.get_wallclock		= get_rtc_noop;
> +	x86_init.resources.probe_roms		= x86_init_noop;
> +	x86_init.resources.reserve_resources	= x86_init_noop;
> +	x86_init.mpparse.find_smp_config	= x86_init_noop;
> +	x86_init.mpparse.get_smp_config		= hv_snp_get_smp_config;
> +
> +	/*
> +	 * Hyper-V SEV-SNP enlightened guest doesn't support ioapic
> +	 * and legacy APIC page read/write. Switch to hv apic here.
> +	 */
> +	disable_ioapic_support();
> +
> +	/* Get processor and mem info. */
> +	processor_count = *(u32 *)__va(EN_SEV_SNP_PROCESSOR_INFO_ADDR);
> +	entry = (struct memory_map_entry *)__va(EN_SEV_SNP_MEM_INFO_ADDR);
> +
> +	/*
> +	 * There is no bootloader/EFI firmware in the SEV SNP guest.
> +	 * E820 table in the memory just describes memory for kernel,
> +	 * ACPI table, cmdline, boot params and ramdisk. The dynamic
> +	 * data(e.g, vcpu number and the rest memory layout) needs to
> +	 * be read from EN_SEV_SNP_PROCESSOR_INFO_ADDR.
> +	 */
> +	for (; entry->numpages != 0; entry++) {
> +		e820_entry = &e820_table->entries[
> +				e820_table->nr_entries - 1];
> +		e820_end = e820_entry->addr + e820_entry->size;
> +		ram_end = (entry->starting_gpn +
> +			   entry->numpages) * PAGE_SIZE;
> +
> +		if (e820_end < entry->starting_gpn * PAGE_SIZE)
> +			e820_end = entry->starting_gpn * PAGE_SIZE;
> +
> +		if (e820_end < ram_end) {
> +			pr_info("Hyper-V: add e820 entry [mem %#018Lx-%#018Lx]\n", e820_end, ram_end - 1);
> +			e820__range_add(e820_end, ram_end - e820_end,
> +					E820_TYPE_RAM);
> +			for (page = e820_end; page < ram_end; page += PAGE_SIZE)
> +				pvalidate((unsigned long)__va(page), RMP_PG_SIZE_4K, true);
> +		}
> +	}
> +}
> +
>  void __init hv_vtom_init(void)
>  {
>  	/*
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index d859d7c5f5e8..7a9a6cdc2ae9 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -50,6 +50,21 @@ extern bool hv_isolation_type_en_snp(void);
> 
>  extern union hv_ghcb * __percpu *hv_ghcb_pg;
> 
> +/*
> + * Hyper-V puts processor and memory layout info
> + * to this address in SEV-SNP enlightened guest.
> + */
> +#define EN_SEV_SNP_PROCESSOR_INFO_ADDR  0x802000
> +#define EN_SEV_SNP_MEM_INFO_ADDR	0x802018
> +
> +struct memory_map_entry {
> +	u64 starting_gpn;
> +	u64 numpages;
> +	u16 type;
> +	u16 flags;
> +	u32 reserved;
> +};
> +
>  int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages);
>  int hv_call_add_logical_proc(int node, u32 lp_index, u32 acpi_id);
>  int hv_call_create_vp(int node, u64 partition_id, u32 vp_index, u32 flags);
> @@ -255,12 +270,14 @@ void hv_ghcb_msr_read(u64 msr, u64 *value);
>  bool hv_ghcb_negotiate_protocol(void);
>  void __noreturn hv_ghcb_terminate(unsigned int set, unsigned int reason);
>  void hv_vtom_init(void);
> +void hv_sev_init_mem_and_cpu(void);
>  #else
>  static inline void hv_ghcb_msr_write(u64 msr, u64 value) {}
>  static inline void hv_ghcb_msr_read(u64 msr, u64 *value) {}
>  static inline bool hv_ghcb_negotiate_protocol(void) { return false; }
>  static inline void hv_ghcb_terminate(unsigned int set, unsigned int reason) {}
>  static inline void hv_vtom_init(void) {}
> +static inline void hv_sev_init_mem_and_cpu(void) {}
>  #endif
> 
>  extern bool hv_isolation_type_snp(void);
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index 9186453251f7..48b9eab3daf6 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -528,6 +528,9 @@ static void __init ms_hyperv_init_platform(void)
>  	if (!(ms_hyperv.features & HV_ACCESS_TSC_INVARIANT))
>  		mark_tsc_unstable("running on Hyper-V");
> 
> +	if (hv_isolation_type_en_snp())
> +		hv_sev_init_mem_and_cpu();
> +
>  	hardlockup_detector_disable();
>  }
> 
> --
> 2.25.1
  

From: Tianyu Lan <ltykernel@gmail.com> Sent: Thursday, June 1, 2023 8:16 AM
> 

[snip]

> 
> +static __init void hv_snp_get_smp_config(unsigned int early)
> +{
> +	/*
> +	 * The "early" is only to be true when there is AMD
> +	 * numa support. Hyper-V AMD SEV-SNP guest may not
> +	 * have numa support. To make sure smp config is
> +	 * always initialized, do that when early is false.
> +	 */

I didn't really understand this comment.  After doing a little research, let
me suggest this wording:

	/*
	 * The "early" parameter can be true only if old-style AMD
	 * Opteron NUMA detection is enabled, which should never be
	 * the case for an SEV-SNP guest.  See CONFIG_AMD_NUMA.
	 * For safety, just do nothing if "early" is true.
	 */

Let me know if this new wording makes sense based on your understanding.

Michael

> +	if (early)
> +		return;
> +
  

On 6/8/2023 10:09 PM, Michael Kelley (LINUX) wrote:
>> +static __init void hv_snp_get_smp_config(unsigned int early)
>> +{
>> +	/*
>> +	 * The "early" is only to be true when there is AMD
>> +	 * numa support. Hyper-V AMD SEV-SNP guest may not
>> +	 * have numa support. To make sure smp config is
>> +	 * always initialized, do that when early is false.
>> +	 */
> I didn't really understand this comment.  After doing a little research, let
> me suggest this wording:
> 
> 	/*
> 	 * The "early" parameter can be true only if old-style AMD
> 	 * Opteron NUMA detection is enabled, which should never be
> 	 * the case for an SEV-SNP guest.  See CONFIG_AMD_NUMA.
> 	 * For safety, just do nothing if "early" is true.
> 	 */
> 
> Let me know if this new wording makes sense based on your understanding.
> 

Yes, it makes sense. Will update. Thanks.
  

On Thu, Jun 08, 2023 at 01:51:35PM +0000, Michael Kelley (LINUX) wrote:
> From: Tianyu Lan <ltykernel@gmail.com> Sent: Thursday, June 1, 2023 8:16 AM
> > 
> > Hyper-V enlightened guest doesn't have boot loader support.
> > Boot Linux kernel directly from hypervisor with data(kernel
> 
> Add a space between "data" and "(kernel"
> 
> > image, initrd and parameter page) and memory for boot up that
> > is initialized via AMD SEV PSP proctol LAUNCH_UPDATE_DATA
> 
> s/proctol/protocol/
> 
> > (Please refernce https://www.amd.com/system/files/TechDocs/55766_SEV-KM_API_Specification.pdf 1.3.1 Launch).
> 
> s/refernce/reference/
> 
> And the link above didn't work for me -- the "55766_SEV-KM_API_Specification.pdf"
> part was separated from the rest of the URL, though it's possible the mangling
> was done by Microsoft's email system.  Please double check that the URL is
> correctly formatted with no spurious spaces.
> 
> Even better, maybe write this as:
> 
> Please reference Section 1.3.1 "Launch" of [1].
> 
> Then put the full link as [1] at the bottom of the commit message.
> 

Tianyu: that document is SEV specific, and does not have the parts that SEV-SNP
uses. For SNP this is the firmware ABI:

https://www.amd.com/system/files/TechDocs/56860.pdf

and the API I think you mean is SNP_LAUNCH_UPDATE.

It would also help to mention that the data at EN_SEV_SNP_PROCESSOR_INFO_ADDR
is loaded as PAGE_TYPE_UNMEASURED.

Thanks,
Jeremi