| Message ID | 1613690194-102905-2-git-send-email-mikelley@microsoft.com |
|---|---|
| State | New |
| Headers | show |
| Series | Enable Linux guests on Hyper-V on ARM64 | expand |
On Thu, Feb 18, 2021 at 03:16:29PM -0800, Michael Kelley wrote: > hyperv-tlfs.h defines Hyper-V interfaces from the Hyper-V Top Level > Functional Spec (TLFS), and #includes the architecture-independent > part of hyperv-tlfs.h in include/asm-generic. The published TLFS > is distinctly oriented to x86/x64, so the ARM64-specific > hyperv-tlfs.h includes information for ARM64 that is not yet formally > published. The TLFS is available here: > > docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs > > mshyperv.h defines Linux-specific structures and routines for > interacting with Hyper-V on ARM64, and #includes the architecture- > independent part of mshyperv.h in include/asm-generic. > > Use these definitions to provide utility functions to make > Hyper-V hypercalls and to get and set Hyper-V provided > registers associated with a virtual processor. > > Signed-off-by: Michael Kelley <mikelley@microsoft.com> Reviewed-by: Wei Liu <wei.liu@kernel.org>
On Thu, Feb 18, 2021 at 03:16:29PM -0800, Michael Kelley wrote: [...] > + > +/* > + * Get the value of a single VP register. One version > + * returns just 64 bits and another returns the full 128 bits. > + * The two versions are separate to avoid complicating the > + * calling sequence for the more frequently used 64 bit version. > + */ > + > +void __hv_get_vpreg_128(u32 msr, > + struct hv_get_vp_registers_input *input, > + struct hv_get_vp_registers_output *res) > +{ > + u64 status; > + > + input->header.partitionid = HV_PARTITION_ID_SELF; > + input->header.vpindex = HV_VP_INDEX_SELF; > + input->header.inputvtl = 0; > + input->element[0].name0 = msr; > + input->element[0].name1 = 0; > + > + > + status = hv_do_hypercall( > + HVCALL_GET_VP_REGISTERS | HV_HYPERCALL_REP_COMP_1, > + input, res); > + > + /* > + * Something is fundamentally broken in the hypervisor if > + * getting a VP register fails. There's really no way to > + * continue as a guest VM, so panic. > + */ > + BUG_ON((status & HV_HYPERCALL_RESULT_MASK) != HV_STATUS_SUCCESS); > +} > + > +u64 hv_get_vpreg(u32 msr) > +{ > + struct hv_get_vp_registers_input *input; > + struct hv_get_vp_registers_output *output; > + u64 result; > + > + /* > + * Allocate a power of 2 size so alignment to that size is > + * guaranteed, since the hypercall input and output areas > + * must not cross a page boundary. > + */ > + input = kzalloc(roundup_pow_of_two(sizeof(input->header) + > + sizeof(input->element[0])), GFP_ATOMIC); > + output = kmalloc(roundup_pow_of_two(sizeof(*output)), GFP_ATOMIC); > + Do we need to BUG_ON(!input || !output)? Or we expect the page fault (for input being NULL) or the failure of hypercall (for output being NULL) to tell us the allocation failed? Hmm.. think a bit more on this, maybe we'd better retry the allocation if it failed. Because say we are under memory pressusre, and only have memory enough for doing one hvcall, and one thread allocates that memory but gets preempted by another thread trying to do another hvcall: <thread 1> hv_get_vpreg(): input = kzalloc(...); output = kmalloc(...); <preempted and switch to thread 2> hv_get_vpreg(): intput = kzalloc(...); // allocation fails, but actually if // we wait for thread 1 to finish its // hvcall, we can get enough memory. , in this case, if thread 2 retried, it might get the enough memory, therefore there is no need to BUG_ON() on allocation failure. That said, I don't think this is likely to happen, and there may be better solutions for this, so maybe we can keep it as it is (assuming that memory allocation for hvcall never fails) and improve later. Regards, Boqun > + __hv_get_vpreg_128(msr, input, output); > + > + result = output->as64.low; > + kfree(input); > + kfree(output); > + return result; > +} > +EXPORT_SYMBOL_GPL(hv_get_vpreg); > + > +void hv_get_vpreg_128(u32 msr, struct hv_get_vp_registers_output *res) > +{ > + struct hv_get_vp_registers_input *input; > + struct hv_get_vp_registers_output *output; > + > + /* > + * Allocate a power of 2 size so alignment to that size is > + * guaranteed, since the hypercall input and output areas > + * must not cross a page boundary. > + */ > + input = kzalloc(roundup_pow_of_two(sizeof(input->header) + > + sizeof(input->element[0])), GFP_ATOMIC); > + output = kmalloc(roundup_pow_of_two(sizeof(*output)), GFP_ATOMIC); > + > + __hv_get_vpreg_128(msr, input, output); > + > + res->as64.low = output->as64.low; > + res->as64.high = output->as64.high; > + kfree(input); > + kfree(output); > +} [...]
From: Boqun Feng <boqun.feng@gmail.com> Sent: Tuesday, February 23, 2021 6:37 PM > > On Thu, Feb 18, 2021 at 03:16:29PM -0800, Michael Kelley wrote: > [...] > > + > > +/* > > + * Get the value of a single VP register. One version > > + * returns just 64 bits and another returns the full 128 bits. > > + * The two versions are separate to avoid complicating the > > + * calling sequence for the more frequently used 64 bit version. > > + */ > > + > > +void __hv_get_vpreg_128(u32 msr, > > + struct hv_get_vp_registers_input *input, > > + struct hv_get_vp_registers_output *res) > > +{ > > + u64 status; > > + > > + input->header.partitionid = HV_PARTITION_ID_SELF; > > + input->header.vpindex = HV_VP_INDEX_SELF; > > + input->header.inputvtl = 0; > > + input->element[0].name0 = msr; > > + input->element[0].name1 = 0; > > + > > + > > + status = hv_do_hypercall( > > + HVCALL_GET_VP_REGISTERS | HV_HYPERCALL_REP_COMP_1, > > + input, res); > > + > > + /* > > + * Something is fundamentally broken in the hypervisor if > > + * getting a VP register fails. There's really no way to > > + * continue as a guest VM, so panic. > > + */ > > + BUG_ON((status & HV_HYPERCALL_RESULT_MASK) != HV_STATUS_SUCCESS); > > +} > > + > > +u64 hv_get_vpreg(u32 msr) > > +{ > > + struct hv_get_vp_registers_input *input; > > + struct hv_get_vp_registers_output *output; > > + u64 result; > > + > > + /* > > + * Allocate a power of 2 size so alignment to that size is > > + * guaranteed, since the hypercall input and output areas > > + * must not cross a page boundary. > > + */ > > + input = kzalloc(roundup_pow_of_two(sizeof(input->header) + > > + sizeof(input->element[0])), GFP_ATOMIC); > > + output = kmalloc(roundup_pow_of_two(sizeof(*output)), GFP_ATOMIC); > > + > > Do we need to BUG_ON(!input || !output)? Or we expect the page fault > (for input being NULL) or the failure of hypercall (for output being > NULL) to tell us the allocation failed? > > Hmm.. think a bit more on this, maybe we'd better retry the allocation > if it failed. Because say we are under memory pressusre, and only have > memory enough for doing one hvcall, and one thread allocates that memory > but gets preempted by another thread trying to do another hvcall: > > <thread 1> > hv_get_vpreg(): > input = kzalloc(...); > output = kmalloc(...); > <preempted and switch to thread 2> > hv_get_vpreg(): > intput = kzalloc(...); // allocation fails, but actually if > // we wait for thread 1 to finish its > // hvcall, we can get enough memory. > > , in this case, if thread 2 retried, it might get the enough memory, > therefore there is no need to BUG_ON() on allocation failure. That said, > I don't think this is likely to happen, and there may be better > solutions for this, so maybe we can keep it as it is (assuming that > memory allocation for hvcall never fails) and improve later. > > Regards, > Boqun Having to do these memory allocations in order to make a hypercall results in a lot of messiness. I've just gone back to try again at doing hv_get_vpreg() and hv_get_vpreg_128() as "fast" hypercalls that pass inputs (and outputs) in registers like hv_set_vpreg(). I have it working now, with some tweaks to arm_smccc_1_1_hvc() to allow outputs in a wider range of registers than just X0 thru X3. This wider range of registers is allowed by the SMCCC version 1.2 and 1.3 specs, so hopefully is acceptable. I'll send out a new version using this "fast" hypercall approach that completely avoids all these memory allocation problems. Michael > > > + __hv_get_vpreg_128(msr, input, output); > > + > > + result = output->as64.low; > > + kfree(input); > > + kfree(output); > > + return result; > > +} > > +EXPORT_SYMBOL_GPL(hv_get_vpreg); > > + > > +void hv_get_vpreg_128(u32 msr, struct hv_get_vp_registers_output *res) > > +{ > > + struct hv_get_vp_registers_input *input; > > + struct hv_get_vp_registers_output *output; > > + > > + /* > > + * Allocate a power of 2 size so alignment to that size is > > + * guaranteed, since the hypercall input and output areas > > + * must not cross a page boundary. > > + */ > > + input = kzalloc(roundup_pow_of_two(sizeof(input->header) + > > + sizeof(input->element[0])), GFP_ATOMIC); > > + output = kmalloc(roundup_pow_of_two(sizeof(*output)), GFP_ATOMIC); > > + > > + __hv_get_vpreg_128(msr, input, output); > > + > > + res->as64.low = output->as64.low; > > + res->as64.high = output->as64.high; > > + kfree(input); > > + kfree(output); > > +} > [...]
diff --git a/MAINTAINERS b/MAINTAINERS index 546aa66..0a22f3a 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8235,6 +8235,9 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux.git F: Documentation/ABI/stable/sysfs-bus-vmbus F: Documentation/ABI/testing/debugfs-hyperv F: Documentation/networking/device_drivers/ethernet/microsoft/netvsc.rst +F: arch/arm64/hyperv +F: arch/arm64/include/asm/hyperv-tlfs.h +F: arch/arm64/include/asm/mshyperv.h F: arch/x86/hyperv F: arch/x86/include/asm/hyperv-tlfs.h F: arch/x86/include/asm/mshyperv.h diff --git a/arch/arm64/Kbuild b/arch/arm64/Kbuild index d646582..7a37608 100644 --- a/arch/arm64/Kbuild +++ b/arch/arm64/Kbuild @@ -3,4 +3,5 @@ obj-y += kernel/ mm/ obj-$(CONFIG_NET) += net/ obj-$(CONFIG_KVM) += kvm/ obj-$(CONFIG_XEN) += xen/ +obj-$(subst m,y,$(CONFIG_HYPERV)) += hyperv/ obj-$(CONFIG_CRYPTO) += crypto/ diff --git a/arch/arm64/hyperv/Makefile b/arch/arm64/hyperv/Makefile new file mode 100644 index 0000000..1697d30 --- /dev/null +++ b/arch/arm64/hyperv/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0 +obj-y := hv_core.o diff --git a/arch/arm64/hyperv/hv_core.c b/arch/arm64/hyperv/hv_core.c new file mode 100644 index 0000000..9a37124 --- /dev/null +++ b/arch/arm64/hyperv/hv_core.c @@ -0,0 +1,167 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Low level utility routines for interacting with Hyper-V. + * + * Copyright (C) 2021, Microsoft, Inc. + * + * Author : Michael Kelley <mikelley@microsoft.com> + */ + + +#include <linux/types.h> +#include <linux/log2.h> +#include <linux/export.h> +#include <linux/mm.h> +#include <linux/slab.h> +#include <linux/hyperv.h> +#include <linux/arm-smccc.h> +#include <linux/vmalloc.h> +#include <linux/module.h> +#include <asm-generic/bug.h> +#include <asm/hyperv-tlfs.h> +#include <asm/mshyperv.h> + +/* + * hv_do_hypercall- Invoke the specified hypercall + */ +u64 hv_do_hypercall(u64 control, void *input, void *output) +{ + u64 input_address; + u64 output_address; + struct arm_smccc_res res; + + input_address = input ? virt_to_phys(input) : 0; + output_address = output ? virt_to_phys(output) : 0; + + arm_smccc_1_1_hvc(HV_FUNC_ID, control, + input_address, output_address, &res); + return res.a0; +} +EXPORT_SYMBOL_GPL(hv_do_hypercall); + +/* + * hv_do_fast_hypercall8 -- Invoke the specified hypercall + * with arguments in registers instead of physical memory. + * Avoids the overhead of virt_to_phys for simple hypercalls. + */ + +u64 hv_do_fast_hypercall8(u16 code, u64 input) +{ + u64 control; + struct arm_smccc_res res; + + control = (u64)code | HV_HYPERCALL_FAST_BIT; + + arm_smccc_1_1_hvc(HV_FUNC_ID, control, input, &res); + return res.a0; +} +EXPORT_SYMBOL_GPL(hv_do_fast_hypercall8); + + +/* + * Set a single VP register to a 64-bit value. + */ +void hv_set_vpreg(u32 msr, u64 value) +{ + struct arm_smccc_res res; + + arm_smccc_1_1_hvc( + HV_FUNC_ID, + HVCALL_SET_VP_REGISTERS | HV_HYPERCALL_FAST_BIT | + HV_HYPERCALL_REP_COMP_1, + HV_PARTITION_ID_SELF, + HV_VP_INDEX_SELF, + msr, + 0, + value, + 0, + &res); + + /* + * Something is fundamentally broken in the hypervisor if + * setting a VP register fails. There's really no way to + * continue as a guest VM, so panic. + */ + BUG_ON((res.a0 & HV_HYPERCALL_RESULT_MASK) != HV_STATUS_SUCCESS); +} +EXPORT_SYMBOL_GPL(hv_set_vpreg); + +/* + * Get the value of a single VP register. One version + * returns just 64 bits and another returns the full 128 bits. + * The two versions are separate to avoid complicating the + * calling sequence for the more frequently used 64 bit version. + */ + +void __hv_get_vpreg_128(u32 msr, + struct hv_get_vp_registers_input *input, + struct hv_get_vp_registers_output *res) +{ + u64 status; + + input->header.partitionid = HV_PARTITION_ID_SELF; + input->header.vpindex = HV_VP_INDEX_SELF; + input->header.inputvtl = 0; + input->element[0].name0 = msr; + input->element[0].name1 = 0; + + + status = hv_do_hypercall( + HVCALL_GET_VP_REGISTERS | HV_HYPERCALL_REP_COMP_1, + input, res); + + /* + * Something is fundamentally broken in the hypervisor if + * getting a VP register fails. There's really no way to + * continue as a guest VM, so panic. + */ + BUG_ON((status & HV_HYPERCALL_RESULT_MASK) != HV_STATUS_SUCCESS); +} + +u64 hv_get_vpreg(u32 msr) +{ + struct hv_get_vp_registers_input *input; + struct hv_get_vp_registers_output *output; + u64 result; + + /* + * Allocate a power of 2 size so alignment to that size is + * guaranteed, since the hypercall input and output areas + * must not cross a page boundary. + */ + input = kzalloc(roundup_pow_of_two(sizeof(input->header) + + sizeof(input->element[0])), GFP_ATOMIC); + output = kmalloc(roundup_pow_of_two(sizeof(*output)), GFP_ATOMIC); + + __hv_get_vpreg_128(msr, input, output); + + result = output->as64.low; + kfree(input); + kfree(output); + return result; +} +EXPORT_SYMBOL_GPL(hv_get_vpreg); + +void hv_get_vpreg_128(u32 msr, struct hv_get_vp_registers_output *res) +{ + struct hv_get_vp_registers_input *input; + struct hv_get_vp_registers_output *output; + + /* + * Allocate a power of 2 size so alignment to that size is + * guaranteed, since the hypercall input and output areas + * must not cross a page boundary. + */ + input = kzalloc(roundup_pow_of_two(sizeof(input->header) + + sizeof(input->element[0])), GFP_ATOMIC); + output = kmalloc(roundup_pow_of_two(sizeof(*output)), GFP_ATOMIC); + + __hv_get_vpreg_128(msr, input, output); + + res->as64.low = output->as64.low; + res->as64.high = output->as64.high; + kfree(input); + kfree(output); +} +EXPORT_SYMBOL_GPL(hv_get_vpreg_128); diff --git a/arch/arm64/include/asm/hyperv-tlfs.h b/arch/arm64/include/asm/hyperv-tlfs.h new file mode 100644 index 0000000..4d964a7 --- /dev/null +++ b/arch/arm64/include/asm/hyperv-tlfs.h @@ -0,0 +1,69 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +/* + * This file contains definitions from the Hyper-V Hypervisor Top-Level + * Functional Specification (TLFS): + * https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs + * + * Copyright (C) 2021, Microsoft, Inc. + * + * Author : Michael Kelley <mikelley@microsoft.com> + */ + +#ifndef _ASM_HYPERV_TLFS_H +#define _ASM_HYPERV_TLFS_H + +#include <linux/types.h> + +/* + * All data structures defined in the TLFS that are shared between Hyper-V + * and a guest VM use Little Endian byte ordering. This matches the default + * byte ordering of Linux running on ARM64, so no special handling is required. + */ + +/* + * These Hyper-V registers provide information equivalent to the CPUID + * instruction on x86/x64. + */ +#define HV_REGISTER_HYPERVISOR_VERSION 0x00000100 /*CPUID 0x40000002 */ +#define HV_REGISTER_FEATURES 0x00000200 /*CPUID 0x40000003 */ +#define HV_REGISTER_ENLIGHTENMENTS 0x00000201 /*CPUID 0x40000004 */ + +/* + * Group C Features. See the asm-generic version of hyperv-tlfs.h + * for a description of Feature Groups. + */ + +/* Crash MSRs available */ +#define HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE BIT(8) + +/* STIMER direct mode is available */ +#define HV_STIMER_DIRECT_MODE_AVAILABLE BIT(13) + +/* + * Synthetic register definitions equivalent to MSRs on x86/x64 + */ +#define HV_REGISTER_CRASH_P0 0x00000210 +#define HV_REGISTER_CRASH_P1 0x00000211 +#define HV_REGISTER_CRASH_P2 0x00000212 +#define HV_REGISTER_CRASH_P3 0x00000213 +#define HV_REGISTER_CRASH_P4 0x00000214 +#define HV_REGISTER_CRASH_CTL 0x00000215 + +#define HV_REGISTER_GUEST_OSID 0x00090002 +#define HV_REGISTER_VP_INDEX 0x00090003 +#define HV_REGISTER_TIME_REF_COUNT 0x00090004 +#define HV_REGISTER_REFERENCE_TSC 0x00090017 + +#define HV_REGISTER_SINT0 0x000A0000 +#define HV_REGISTER_SCONTROL 0x000A0010 +#define HV_REGISTER_SIEFP 0x000A0012 +#define HV_REGISTER_SIMP 0x000A0013 +#define HV_REGISTER_EOM 0x000A0014 + +#define HV_REGISTER_STIMER0_CONFIG 0x000B0000 +#define HV_REGISTER_STIMER0_COUNT 0x000B0001 + +#include <asm-generic/hyperv-tlfs.h> + +#endif diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h new file mode 100644 index 0000000..44ee012 --- /dev/null +++ b/arch/arm64/include/asm/mshyperv.h @@ -0,0 +1,55 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +/* + * Linux-specific definitions for managing interactions with Microsoft's + * Hyper-V hypervisor. The definitions in this file are specific to + * the ARM64 architecture. See include/asm-generic/mshyperv.h for + * definitions are that architecture independent. + * + * Definitions that are specified in the Hyper-V Top Level Functional + * Spec (TLFS) should not go in this file, but should instead go in + * hyperv-tlfs.h. + * + * Copyright (C) 2021, Microsoft, Inc. + * + * Author : Michael Kelley <mikelley@microsoft.com> + */ + +#ifndef _ASM_MSHYPERV_H +#define _ASM_MSHYPERV_H + +#include <linux/types.h> +#include <linux/arm-smccc.h> +#include <asm/hyperv-tlfs.h> + +/* + * Declare calls to get and set Hyper-V VP register values on ARM64, which + * requires a hypercall. + */ + +extern void hv_set_vpreg(u32 reg, u64 value); +extern u64 hv_get_vpreg(u32 reg); +extern void __hv_get_vpreg_128(u32 reg, struct hv_get_vp_registers_input *input, + struct hv_get_vp_registers_output *result); + +static inline void hv_set_register(unsigned int reg, u64 value) +{ + hv_set_vpreg(reg, value); +} + +static inline u64 hv_get_register(unsigned int reg) +{ + return hv_get_vpreg(reg); +} + +/* SMCCC hypercall parameters */ +#define HV_SMCCC_FUNC_NUMBER 1 +#define HV_FUNC_ID ARM_SMCCC_CALL_VAL( \ + ARM_SMCCC_STD_CALL, \ + ARM_SMCCC_SMC_64, \ + ARM_SMCCC_OWNER_VENDOR_HYP, \ + HV_SMCCC_FUNC_NUMBER) + +#include <asm-generic/mshyperv.h> + +#endif
hyperv-tlfs.h defines Hyper-V interfaces from the Hyper-V Top Level Functional Spec (TLFS), and #includes the architecture-independent part of hyperv-tlfs.h in include/asm-generic. The published TLFS is distinctly oriented to x86/x64, so the ARM64-specific hyperv-tlfs.h includes information for ARM64 that is not yet formally published. The TLFS is available here: docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs mshyperv.h defines Linux-specific structures and routines for interacting with Hyper-V on ARM64, and #includes the architecture- independent part of mshyperv.h in include/asm-generic. Use these definitions to provide utility functions to make Hyper-V hypercalls and to get and set Hyper-V provided registers associated with a virtual processor. Signed-off-by: Michael Kelley <mikelley@microsoft.com> --- MAINTAINERS | 3 + arch/arm64/Kbuild | 1 + arch/arm64/hyperv/Makefile | 2 + arch/arm64/hyperv/hv_core.c | 167 +++++++++++++++++++++++++++++++++++ arch/arm64/include/asm/hyperv-tlfs.h | 69 +++++++++++++++ arch/arm64/include/asm/mshyperv.h | 55 ++++++++++++ 6 files changed, 297 insertions(+) create mode 100644 arch/arm64/hyperv/Makefile create mode 100644 arch/arm64/hyperv/hv_core.c create mode 100644 arch/arm64/include/asm/hyperv-tlfs.h create mode 100644 arch/arm64/include/asm/mshyperv.h