On 5/23/25 9:27 AM, Radim KrÄmáŠwrote:
2025-05-23T17:29:49+02:00, Clément Léger <cleger@xxxxxxxxxxxx>:
On 23/05/2025 15:05, Radim Krčmář wrote:
2025-05-23T12:19:30+02:00, Clément Léger <cleger@xxxxxxxxxxxx>:
+++ b/arch/riscv/kvm/vcpu_sbi_fwft.c
+static const enum sbi_fwft_feature_t kvm_fwft_defined_features[] = {
+ SBI_FWFT_MISALIGNED_EXC_DELEG,
+ SBI_FWFT_LANDING_PAD,
+ SBI_FWFT_SHADOW_STACK,
+ SBI_FWFT_DOUBLE_TRAP,
+ SBI_FWFT_PTE_AD_HW_UPDATING,
+ SBI_FWFT_POINTER_MASKING_PMLEN,
+};
How will userspace control which subset of these features is allowed in
the guest?
(We can reuse the KVM SBI extension interface if we don't want to add a
FWFT specific ONE_REG.)
Hi Radim,
I didn't looked at that part. But most likely using the kvm one reg
interface seems ok like what is done for STA ? We could have per feature
override with one reg per feature.
Sounds fine.
Yeah. We can have a follow up series for SBI FWFT state that allows user
space to toggle each state individually.
Is this something blocking though ? We'd like to merge FWFT once SBI 3.0
is ratified so that would be nice not delaying it too much. I'll take a
look at it to see if it isn't too long to implement.
Not blocking, but I would at least default FWFT to disabled, because
current userspace cannot handle [14/14]. (Well... save/restore was
probably broken even before, but let's try to not make it worse. :])
User space can not enable or disable misaligned access delegation as
there is no interface for now rightly pointed by you. I guess supporting
that would be quicker than fixing the broader guest save/restore
anyways. Isn't it ?
We can have the patches ready for the next MW for FWFT one reg interface.
Thanks.
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