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drivers/virt: pkvm: Add initial support for running as a protected guest

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Implement a pKVM protected guest driver to probe the presence of pKVM
and determine the memory protection granule using the HYP_MEMINFO
hypercall.

Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240830130150.8568-3-will@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Will Deacon 2024-08-30 14:01:45 +01:00
parent 0ba5b4ba61
commit a06c3fad49
8 changed files with 88 additions and 0 deletions
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22
Documentation/virt/kvm/arm/hypercalls.rst
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@ -44,3 +44,25 @@ Provides a discovery mechanism for other KVM/arm64 hypercalls.
----------------------------------------
See ptp_kvm.rst
``ARM_SMCCC_KVM_FUNC_HYP_MEMINFO``
----------------------------------
Query the memory protection parameters for a pKVM protected virtual machine.
+---------------------+-------------------------------------------------------------+
| Presence: | Optional; pKVM protected guests only. |
+---------------------+-------------------------------------------------------------+
| Calling convention: | HVC64 |
+---------------------+----------+--------------------------------------------------+
| Function ID: | (uint32) | 0xC6000002 |
+---------------------+----------+----+---------------------------------------------+
| Arguments: | (uint64) | R1 | Reserved / Must be zero |
| +----------+----+---------------------------------------------+
| | (uint64) | R2 | Reserved / Must be zero |
| +----------+----+---------------------------------------------+
| | (uint64) | R3 | Reserved / Must be zero |
+---------------------+----------+----+---------------------------------------------+
| Return Values: | (int64) | R0 | ``INVALID_PARAMETER (-3)`` on error, else |
| | | | memory protection granule in bytes |
+---------------------+----------+----+---------------------------------------------+

7
arch/arm64/include/asm/hypervisor.h
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@ -7,8 +7,15 @@
void kvm_init_hyp_services(void);
bool kvm_arm_hyp_service_available(u32 func_id);
#ifdef CONFIG_ARM_PKVM_GUEST
void pkvm_init_hyp_services(void);
#else
static inline void pkvm_init_hyp_services(void) { };
#endif
static inline void kvm_arch_init_hyp_services(void)
{
pkvm_init_hyp_services();
};
#endif

2
drivers/virt/coco/Kconfig
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@ -9,6 +9,8 @@ config TSM_REPORTS
source "drivers/virt/coco/efi_secret/Kconfig"
source "drivers/virt/coco/pkvm-guest/Kconfig"
source "drivers/virt/coco/sev-guest/Kconfig"
source "drivers/virt/coco/tdx-guest/Kconfig"

1
drivers/virt/coco/Makefile
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@ -4,5 +4,6 @@
#
obj-$(CONFIG_TSM_REPORTS) += tsm.o
obj-$(CONFIG_EFI_SECRET) += efi_secret/
obj-$(CONFIG_ARM_PKVM_GUEST) += pkvm-guest/
obj-$(CONFIG_SEV_GUEST) += sev-guest/
obj-$(CONFIG_INTEL_TDX_GUEST) += tdx-guest/

10
drivers/virt/coco/pkvm-guest/Kconfig Normal file
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@ -0,0 +1,10 @@
config ARM_PKVM_GUEST
bool "Arm pKVM protected guest driver"
depends on ARM64
help
Protected guests running under the pKVM hypervisor on arm64
are isolated from the host and must issue hypercalls to enable
interaction with virtual devices. This driver implements
support for probing and issuing these hypercalls.
If unsure, say 'N'.

2
drivers/virt/coco/pkvm-guest/Makefile Normal file
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@ -0,0 +1,2 @@
# SPDX-License-Identifier: GPL-2.0-only
obj-$(CONFIG_ARM_PKVM_GUEST) += arm-pkvm-guest.o

37
drivers/virt/coco/pkvm-guest/arm-pkvm-guest.c Normal file
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@ -0,0 +1,37 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
* Support for the hypercall interface exposed to protected guests by
* pKVM.
*
* Author: Will Deacon <will@kernel.org>
* Copyright (C) 2024 Google LLC
*/
#include <linux/arm-smccc.h>
#include <linux/array_size.h>
#include <linux/mm.h>
#include <asm/hypervisor.h>
static size_t pkvm_granule;
void pkvm_init_hyp_services(void)
{
int i;
struct arm_smccc_res res;
const u32 funcs[] = {
ARM_SMCCC_KVM_FUNC_HYP_MEMINFO,
};
for (i = 0; i < ARRAY_SIZE(funcs); ++i) {
if (!kvm_arm_hyp_service_available(funcs[i]))
return;
}
arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_HYP_MEMINFO_FUNC_ID,
0, 0, 0, &res);
if (res.a0 > PAGE_SIZE) /* Includes error codes */
return;
pkvm_granule = res.a0;
}

7
include/linux/arm-smccc.h
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@ -115,6 +115,7 @@
/* KVM "vendor specific" services */
#define ARM_SMCCC_KVM_FUNC_FEATURES 0
#define ARM_SMCCC_KVM_FUNC_PTP 1
#define ARM_SMCCC_KVM_FUNC_HYP_MEMINFO 2
#define ARM_SMCCC_KVM_FUNC_FEATURES_2 127
#define ARM_SMCCC_KVM_NUM_FUNCS 128
@ -137,6 +138,12 @@
ARM_SMCCC_OWNER_VENDOR_HYP, \
ARM_SMCCC_KVM_FUNC_PTP)
#define ARM_SMCCC_VENDOR_HYP_KVM_HYP_MEMINFO_FUNC_ID \
ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
ARM_SMCCC_SMC_64, \
ARM_SMCCC_OWNER_VENDOR_HYP, \
ARM_SMCCC_KVM_FUNC_HYP_MEMINFO)
/* ptp_kvm counter type ID */
#define KVM_PTP_VIRT_COUNTER 0
#define KVM_PTP_PHYS_COUNTER 1