Messages in this thread | | | Date | Wed, 7 Dec 2022 01:02:06 +0000 | Subject | [PATCH v9 0/4] Add throttling detection to sev-guest | From | Dionna Glaze <> |
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The guest request synchronous API from SEV-SNP VMs to the host's security processor consumes a global resource. For this reason, AMD's docs recommend that the host implements a throttling mechanism. In order for the guest to know it's been throttled and should try its request again, we need some good-faith communication from the host that the request has been throttled.
These patches work with the existing /dev/sev-guest ABI to detect a throttling code.
Changes from v8: * Added documentation changes. * Changed commit messages to use passive voice. * Simplified control flow for __sev_platform_init_locked. Changes from v7: * Replaced handle_guest_request arguments msg_ver and fw_err with a pointer to the snp_guest_request_ioctl argument struct. Changes from v6: * Rebased on the IV reuse fix patch * renamed rate_hz to rate_s and fixed its MODULE_PARM_DESC to use the correct variable name. * Changed sleep_timeout_interrutible (not defined) to schedule_timeout_interruptible. Changes from v5: * Fixed commit prefix text * Added all get_maintainers.pl folks to commits' Cc tags * Changed SET_RET_NO_FW_CALL commit's metadata to show pgonda signs off and is the author. Changes from v4: * Clarified comment on SEV_RET_NO_FW_CALL * Changed ratelimit loop to use sleep_timeout_interruptible Changes from v3: * sev-guest ratelimits itself to one request twice a second. * Fixed a type signature to use u64 instead of unsigned int * Set *exitinfo2 unconditionally after the ghcb_hv_call. Changes from v2: * Codified the non-firmware-call firmware error code as (u32)-1. * Changed sev_issue_guest_request unsigned long *fw_err argument to u64 *exitinfo2 to more accurately and type-safely describe the value that it outputs. * Changed sev_issue_guest_request to always set its exitinfo2 argument to either the non-firmware-call error code, the EXIT_INFO_2 returned from the VMM if the request failed, or 0 on success. This fixes a bug that returned uninitialized kernel stack memory to the user when there is no error. * Changed the throttle behavior to retry in the driver instead of returning -EAGAIN, due to possible message sequence number reuse on different message contents.
Changes from v1: * Changed throttle error code to 2
Cc: Tom Lendacky <Thomas.Lendacky@amd.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Peter Gonda <pgonda@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de>
Signed-off-by: Dionna Glaze <dionnaglaze@google.com>
Dionna Glaze (3): x86/sev: Change snp_guest_issue_request's fw_err virt: sev-guest: Remove err in handle_guest_request virt: sev-guest: interpret VMM errors from guest request
Peter Gonda (1): crypto: ccp - Name -1 return value as SEV_RET_NO_FW_CALL
Documentation/virt/coco/sev-guest.rst | 21 ++++--- arch/x86/include/asm/sev.h | 4 +- arch/x86/kernel/sev.c | 10 ++-- drivers/crypto/ccp/sev-dev.c | 22 ++++--- drivers/virt/coco/sev-guest/sev-guest.c | 76 +++++++++++++++++-------- include/uapi/linux/psp-sev.h | 7 +++ include/uapi/linux/sev-guest.h | 18 +++++- 7 files changed, 112 insertions(+), 46 deletions(-)
-- 2.39.0.rc0.267.gcb52ba06e7-goog
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