On 4/3/23 10:43, Tianyu Lan wrote:
> From: Tianyu Lan <tiala@xxxxxxxxxxxxx>
>
> Read processor amd memory info from specific address which are
> populated by Hyper-V. Initialize smp cpu related ops, pvalidate
> system memory and add it into e820 table.
>
> Signed-off-by: Tianyu Lan <tiala@xxxxxxxxxxxxx>
> ---
> arch/x86/hyperv/ivm.c | 78 +++++++++++++++++++++++++++++++++
> arch/x86/include/asm/mshyperv.h | 16 +++++++
> arch/x86/kernel/cpu/mshyperv.c | 3 ++
> 3 files changed, 97 insertions(+)
>
> diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
> index 368b2731950e..fa4de2761460 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 +62,22 @@ union hv_ghcb {
>
> static u16 hv_ghcb_version __ro_after_init;
>
> +static u32 processor_count;
> +
> +static __init void hv_snp_get_smp_config(unsigned int early)
> +{
> + if (!early) {
> + 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++;
> + }
> + }
> +}
Folks, please minimize indentation:
if (early)
return;
It would also be nice to see *some* explanation in the changelog or
comments about why it's best and correct to just do nothing if early==1.
Also, this _consumes_ data from hv_sev_init_mem_and_cpu(). It would
make more sense to me to have them ordered the other way.
hv_sev_init_mem_and_cpu() first, this second.
> u64 hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_size)
> {
> union hv_ghcb *hv_ghcb;
> @@ -356,6 +377,63 @@ static bool hv_is_private_mmio(u64 addr)
> return false;
> }
>
> +__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 and so roms,
> + * bios regions and reserve resources are not
> + * available. Set these callback to NULL.
> + */
> + x86_platform.legacy.reserve_bios_regions = 0;
> + 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;
This is one of those places that vertical alignment adds clarity:
> + 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;
See? 3 noops and only one actual implemented function. Clear as day now.
> + /*> + * Hyper-V SEV-SNP enlightened guest doesn't support ioapic
> + * and legacy APIC page read/write. Switch to hv apic here.
> + */
> + disable_ioapic_support();
Do these systems have X86_FEATURE_APIC set? Why is this needed in
addition to the architectural enumeration that already exists?
Is there any other place in the kernel that has this one-off disabling
of the APIC?
> + /* Read processor number and memory layout. */
> + processor_count = *(u32 *)__va(EN_SEV_SNP_PROCESSOR_INFO_ADDR);
> + entry = (struct memory_map_entry *)(__va(EN_SEV_SNP_PROCESSOR_INFO_ADDR)
> + + sizeof(struct memory_map_entry));
Ick.
There are a lot of ways to do this. But, this is an awfully ugly way.
struct snp_processor_info {
u32 processor_count;
struct memory_map_entry[] entries;
}
struct snp_processor_info *snp_pi =
__va(EN_SEV_SNP_PROCESSOR_INFO_ADDR);
processor_count = snp_pi->processor_count;
Then, have your for() loop through snp_pi->entries;
Actually, I'm not _quite_ sure that processor_count and entries are next
to each other. But, either way, I do think a struct makes sense.
Also, what guarantees that EN_SEV_SNP_PROCESSOR_INFO_ADDR is mapped?
It's up above 8MB which I don't remember off the top of my head as being
a special address.
> + /*
> + * E820 table in the memory just describes memory for
> + * kernel, ACPI table, cmdline, boot params and ramdisk.
> + * Hyper-V popoulates the rest memory layout in the EN_SEV_
> + * SNP_PROCESSOR_INFO_ADDR.
> + */
Really? That is not very cool. We need a better explanation of why
there was no way to use the decades-old e820 or EFI memory map and why
this needs to be a special snowflake.
> + 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);
> + }
> + }
> +}
Oh, is this just about having a pre-accepted area and a non-accepted
area? Is this basically another one-off implementation of unaccepted
memory ... that doesn't use the EFI standard?
> void __init hv_vtom_init(void)
> {
> /*
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index 3c15e23162e7..a4a59007b5f2 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -41,6 +41,20 @@ 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
> +
> +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);
> @@ -246,12 +260,14 @@ void hv_ghcb_msr_read(u64 msr, u64 *value);
> bool hv_ghcb_negotiate_protocol(void);
> void 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 2f2dcb2370b6..71820bbf9e90 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -529,6 +529,9 @@ 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();
> }
>
