Messages in this thread | | | From | Dionna Amalie Glaze <> | Date | Thu, 27 Oct 2022 08:53:54 -0700 | Subject | Re: [PATCH v4 0/4] Add throttling detection to sev-guest |
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Pinging y'all in case you haven't seen v4 :)
On Mon, Oct 24, 2022 at 3:47 PM Dionna Glaze <dionnaglaze@google.com> wrote: > > 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 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> > > Signed-off-by: Dionna Glaze <dionnaglaze@google.com> > > Dionna Glaze (4): > ccp: Name -1 return value as SEV_RET_NO_FW_CALL > x86/sev: Change snp_guest_issue_request's fw_err > virt/coco/sev-guest: Remove err in handle_guest_request > virt/coco/sev-guest: interpret VMM errors from guest request > > arch/x86/include/asm/sev.h | 4 +- > arch/x86/kernel/sev.c | 10 ++-- > drivers/crypto/ccp/sev-dev.c | 2 +- > drivers/virt/coco/sev-guest/sev-guest.c | 61 ++++++++++++++++++++----- > include/uapi/linux/psp-sev.h | 7 +++ > include/uapi/linux/sev-guest.h | 18 +++++++- > 6 files changed, 82 insertions(+), 20 deletions(-) > > -- > 2.38.0.135.g90850a2211-goog >
-- -Dionna Glaze, PhD (she/her)
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