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Date: Wed, 26 Jul 2023 09:56:45 +0530
From: Jinank Jain <jinankjain@...ux.microsoft.com>
To: Tianyu Lan <ltykernel@...il.com>, kys@...rosoft.com,
haiyangz@...rosoft.com, wei.liu@...nel.org, decui@...rosoft.com,
tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
daniel.lezcano@...aro.org, arnd@...db.de,
michael.h.kelley@...rosoft.com
Cc: Tianyu Lan <tiala@...rosoft.com>, linux-arch@...r.kernel.org,
linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
vkuznets@...hat.com, Michael Kelley <mikelley@...rosoft.com>
Subject: Re: [PATCH V3 7/9] x86/hyperv: Initialize cpu and memory for SEV-SNP
enlightened guest
Hi Tianyu,
On 7/18/2023 8:53 AM, Tianyu Lan wrote:
> From: Tianyu Lan <tiala@...rosoft.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 protocol (Please reference
> Section 4.5 Launching a Guest of [1]).
>
> Kernel needs to read processor and memory info from EN_SEV_
> SNP_PROCESSOR/MEM_INFO_ADDR address which are populated by
> Hyper-V. The data is prepared by hypervisor via SNP_
> LAUNCH_UPDATE with page type SNP_PAGE_TYPE_UNMEASURED and
> Initialize smp cpu related ops, validate system memory and
> add them into e820 table.
>
> [1]: https://www.amd.com/system/files/TechDocs/56860.pdf
> Reviewed-by: Michael Kelley <mikelley@...rosoft.com>
> Signed-off-by: Tianyu Lan <tiala@...rosoft.com>
> ---
> Change since v2:
> * Update change log.
> ---
> 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 b2b5cb19fac9..ede47c8264e0 100644
> --- a/arch/x86/hyperv/ivm.c
> +++ b/arch/x86/hyperv/ivm.c
> @@ -18,6 +18,11 @@
> #include <asm/mshyperv.h>
> #include <asm/hypervisor.h>
> #include <asm/mtrr.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
>
> @@ -58,6 +63,8 @@ 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;
> @@ -357,6 +364,92 @@ static bool hv_is_private_mmio(u64 addr)
> return false;
> }
>
> +static __init void hv_snp_get_smp_config(unsigned int early)
> +{
> + /*
> + * 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.
> + */
> + 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();
Where are we switching hv_apic? May I am missing something here?
Also in my experiments I have seen that if we don't enable I/O Apic
legacy serial console does not seem to work for SEV-SNP guests.
> +
> + /* 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 025eda129d99..e57df590846a 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);
> @@ -234,12 +249,14 @@ 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 5398fb2f4d39..d3bb921ee7fe 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();
> }
>
Regards,
Jinank
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