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KVM: SEV: Add KVM_SEV_SNP_LAUNCH_START command

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KVM_SEV_SNP_LAUNCH_START begins the launch process for an SEV-SNP guest.
The command initializes a cryptographic digest context used to construct
the measurement of the guest. Other commands can then at that point be
used to load/encrypt data into the guest's initial launch image.

For more information see the SEV-SNP specification.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Co-developed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Message-ID: <20240501085210.2213060-6-michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Brijesh Singh 2024-05-01 03:51:55 -05:00 committed by Paolo Bonzini
parent 1dfe571c12
commit 136d8bc931
4 changed files with 212 additions and 4 deletions
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28
Documentation/virt/kvm/x86/amd-memory-encryption.rst
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@ -466,6 +466,30 @@ issued by the hypervisor to make the guest ready for execution.
Returns: 0 on success, -negative on error
18. KVM_SEV_SNP_LAUNCH_START
----------------------------
The KVM_SNP_LAUNCH_START command is used for creating the memory encryption
context for the SEV-SNP guest. It must be called prior to issuing
KVM_SEV_SNP_LAUNCH_UPDATE or KVM_SEV_SNP_LAUNCH_FINISH;
Parameters (in): struct kvm_sev_snp_launch_start
Returns: 0 on success, -negative on error
::
struct kvm_sev_snp_launch_start {
__u64 policy; /* Guest policy to use. */
__u8 gosvw[16]; /* Guest OS visible workarounds. */
__u16 flags; /* Must be zero. */
__u8 pad0[6];
__u64 pad1[4];
};
See SNP_LAUNCH_START in the SEV-SNP specification [snp-fw-abi]_ for further
details on the input parameters in ``struct kvm_sev_snp_launch_start``.
Device attribute API
====================
@ -497,9 +521,11 @@ References
==========
See [white-paper]_, [api-spec]_, [amd-apm]_ and [kvm-forum]_ for more info.
See [white-paper]_, [api-spec]_, [amd-apm]_, [kvm-forum]_, and [snp-fw-abi]_
for more info.
.. [white-paper] https://developer.amd.com/wordpress/media/2013/12/AMD_Memory_Encryption_Whitepaper_v7-Public.pdf
.. [api-spec] https://support.amd.com/TechDocs/55766_SEV-KM_API_Specification.pdf
.. [amd-apm] https://support.amd.com/TechDocs/24593.pdf (section 15.34)
.. [kvm-forum] https://www.linux-kvm.org/images/7/74/02x08A-Thomas_Lendacky-AMDs_Virtualizatoin_Memory_Encryption_Technology.pdf
.. [snp-fw-abi] https://www.amd.com/system/files/TechDocs/56860.pdf

11
arch/x86/include/uapi/asm/kvm.h
View File

@ -697,6 +697,9 @@ enum sev_cmd_id {
/* Second time is the charm; improved versions of the above ioctls. */
KVM_SEV_INIT2,
/* SNP-specific commands */
KVM_SEV_SNP_LAUNCH_START = 100,
KVM_SEV_NR_MAX,
};
@ -824,6 +827,14 @@ struct kvm_sev_receive_update_data {
__u32 pad2;
};
struct kvm_sev_snp_launch_start {
__u64 policy;
__u8 gosvw[16];
__u16 flags;
__u8 pad0[6];
__u64 pad1[4];
};
#define KVM_X2APIC_API_USE_32BIT_IDS (1ULL << 0)
#define KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK (1ULL << 1)

176
arch/x86/kvm/svm/sev.c
View File

@ -25,6 +25,7 @@
#include <asm/fpu/xcr.h>
#include <asm/fpu/xstate.h>
#include <asm/debugreg.h>
#include <asm/sev.h>
#include "mmu.h"
#include "x86.h"
@ -59,6 +60,21 @@ static u64 sev_supported_vmsa_features;
#define AP_RESET_HOLD_NAE_EVENT 1
#define AP_RESET_HOLD_MSR_PROTO 2
/* As defined by SEV-SNP Firmware ABI, under "Guest Policy". */
#define SNP_POLICY_MASK_API_MINOR GENMASK_ULL(7, 0)
#define SNP_POLICY_MASK_API_MAJOR GENMASK_ULL(15, 8)
#define SNP_POLICY_MASK_SMT BIT_ULL(16)
#define SNP_POLICY_MASK_RSVD_MBO BIT_ULL(17)
#define SNP_POLICY_MASK_DEBUG BIT_ULL(19)
#define SNP_POLICY_MASK_SINGLE_SOCKET BIT_ULL(20)
#define SNP_POLICY_MASK_VALID (SNP_POLICY_MASK_API_MINOR | \
SNP_POLICY_MASK_API_MAJOR | \
SNP_POLICY_MASK_SMT | \
SNP_POLICY_MASK_RSVD_MBO | \
SNP_POLICY_MASK_DEBUG | \
SNP_POLICY_MASK_SINGLE_SOCKET)
static u8 sev_enc_bit;
static DECLARE_RWSEM(sev_deactivate_lock);
static DEFINE_MUTEX(sev_bitmap_lock);
@ -69,6 +85,8 @@ static unsigned int nr_asids;
static unsigned long *sev_asid_bitmap;
static unsigned long *sev_reclaim_asid_bitmap;
static int snp_decommission_context(struct kvm *kvm);
struct enc_region {
struct list_head list;
unsigned long npages;
@ -95,12 +113,17 @@ static int sev_flush_asids(unsigned int min_asid, unsigned int max_asid)
down_write(&sev_deactivate_lock);
wbinvd_on_all_cpus();
ret = sev_guest_df_flush(&error);
if (sev_snp_enabled)
ret = sev_do_cmd(SEV_CMD_SNP_DF_FLUSH, NULL, &error);
else
ret = sev_guest_df_flush(&error);
up_write(&sev_deactivate_lock);
if (ret)
pr_err("SEV: DF_FLUSH failed, ret=%d, error=%#x\n", ret, error);
pr_err("SEV%s: DF_FLUSH failed, ret=%d, error=%#x\n",
sev_snp_enabled ? "-SNP" : "", ret, error);
return ret;
}
@ -1998,6 +2021,106 @@ int sev_dev_get_attr(u32 group, u64 attr, u64 *val)
}
}
/*
* The guest context contains all the information, keys and metadata
* associated with the guest that the firmware tracks to implement SEV
* and SNP features. The firmware stores the guest context in hypervisor
* provide page via the SNP_GCTX_CREATE command.
*/
static void *snp_context_create(struct kvm *kvm, struct kvm_sev_cmd *argp)
{
struct sev_data_snp_addr data = {};
void *context;
int rc;
/* Allocate memory for context page */
context = snp_alloc_firmware_page(GFP_KERNEL_ACCOUNT);
if (!context)
return NULL;
data.address = __psp_pa(context);
rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_GCTX_CREATE, &data, &argp->error);
if (rc) {
pr_warn("Failed to create SEV-SNP context, rc %d fw_error %d",
rc, argp->error);
snp_free_firmware_page(context);
return NULL;
}
return context;
}
static int snp_bind_asid(struct kvm *kvm, int *error)
{
struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
struct sev_data_snp_activate data = {0};
data.gctx_paddr = __psp_pa(sev->snp_context);
data.asid = sev_get_asid(kvm);
return sev_issue_cmd(kvm, SEV_CMD_SNP_ACTIVATE, &data, error);
}
static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
{
struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
struct sev_data_snp_launch_start start = {0};
struct kvm_sev_snp_launch_start params;
int rc;
if (!sev_snp_guest(kvm))
return -ENOTTY;
if (copy_from_user(&params, u64_to_user_ptr(argp->data), sizeof(params)))
return -EFAULT;
/* Don't allow userspace to allocate memory for more than 1 SNP context. */
if (sev->snp_context)
return -EINVAL;
sev->snp_context = snp_context_create(kvm, argp);
if (!sev->snp_context)
return -ENOTTY;
if (params.flags)
return -EINVAL;
if (params.policy & ~SNP_POLICY_MASK_VALID)
return -EINVAL;
/* Check for policy bits that must be set */
if (!(params.policy & SNP_POLICY_MASK_RSVD_MBO) ||
!(params.policy & SNP_POLICY_MASK_SMT))
return -EINVAL;
if (params.policy & SNP_POLICY_MASK_SINGLE_SOCKET)
return -EINVAL;
start.gctx_paddr = __psp_pa(sev->snp_context);
start.policy = params.policy;
memcpy(start.gosvw, params.gosvw, sizeof(params.gosvw));
rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_LAUNCH_START, &start, &argp->error);
if (rc) {
pr_debug("%s: SEV_CMD_SNP_LAUNCH_START firmware command failed, rc %d\n",
__func__, rc);
goto e_free_context;
}
sev->fd = argp->sev_fd;
rc = snp_bind_asid(kvm, &argp->error);
if (rc) {
pr_debug("%s: Failed to bind ASID to SEV-SNP context, rc %d\n",
__func__, rc);
goto e_free_context;
}
return 0;
e_free_context:
snp_decommission_context(kvm);
return rc;
}
int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
{
struct kvm_sev_cmd sev_cmd;
@ -2021,6 +2144,15 @@ int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
goto out;
}
/*
* Once KVM_SEV_INIT2 initializes a KVM instance as an SNP guest, only
* allow the use of SNP-specific commands.
*/
if (sev_snp_guest(kvm) && sev_cmd.id < KVM_SEV_SNP_LAUNCH_START) {
r = -EPERM;
goto out;
}
switch (sev_cmd.id) {
case KVM_SEV_ES_INIT:
if (!sev_es_enabled) {
@ -2085,6 +2217,9 @@ int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
case KVM_SEV_RECEIVE_FINISH:
r = sev_receive_finish(kvm, &sev_cmd);
break;
case KVM_SEV_SNP_LAUNCH_START:
r = snp_launch_start(kvm, &sev_cmd);
break;
default:
r = -EINVAL;
goto out;
@ -2280,6 +2415,31 @@ e_source_fput:
return ret;
}
static int snp_decommission_context(struct kvm *kvm)
{
struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
struct sev_data_snp_addr data = {};
int ret;
/* If context is not created then do nothing */
if (!sev->snp_context)
return 0;
/* Do the decommision, which will unbind the ASID from the SNP context */
data.address = __sme_pa(sev->snp_context);
down_write(&sev_deactivate_lock);
ret = sev_do_cmd(SEV_CMD_SNP_DECOMMISSION, &data, NULL);
up_write(&sev_deactivate_lock);
if (WARN_ONCE(ret, "Failed to release guest context, ret %d", ret))
return ret;
snp_free_firmware_page(sev->snp_context);
sev->snp_context = NULL;
return 0;
}
void sev_vm_destroy(struct kvm *kvm)
{
struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
@ -2321,7 +2481,17 @@ void sev_vm_destroy(struct kvm *kvm)
}
}
sev_unbind_asid(kvm, sev->handle);
if (sev_snp_guest(kvm)) {
/*
* Decomission handles unbinding of the ASID. If it fails for
* some unexpected reason, just leak the ASID.
*/
if (snp_decommission_context(kvm))
return;
} else {
sev_unbind_asid(kvm, sev->handle);
}
sev_asid_free(sev);
}

1
arch/x86/kvm/svm/svm.h
View File

@ -93,6 +93,7 @@ struct kvm_sev_info {
struct list_head mirror_entry; /* Use as a list entry of mirrors */
struct misc_cg *misc_cg; /* For misc cgroup accounting */
atomic_t migration_in_progress;
void *snp_context; /* SNP guest context page */
};
struct kvm_svm {