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    SubjectRe: [PATCH v3 3/3] arm64/kvm: Fine grain _EL2 system registers list that affect nested virtualization
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    Hi Miguel,

    On 10/13/23 20:41, Miguel Luis wrote:
    > Hi Eric,
    >
    >> On 12 Oct 2023, at 15:22, Eric Auger <eric.auger@redhat.com> wrote:
    >>
    >> Hi Miguel,
    >>
    >> On 10/11/23 20:01, Miguel Luis wrote:
    >>> Implement a fine grained approach in the _EL2 sysreg ranges.
    >>>
    >>> Fixes: d0fc0a2519a6 ("KVM: arm64: nv: Add trap forwarding for HCR_EL2")
    >>> Signed-off-by: Miguel Luis <miguel.luis@oracle.com>
    >>> ---
    >>> arch/arm64/kvm/emulate-nested.c | 88 ++++++++++++++++++++++++++++++---
    >>> 1 file changed, 82 insertions(+), 6 deletions(-)
    >>>
    >>> diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c
    >>> index 9ced1bf0c2b7..3af49e130ee6 100644
    >>> --- a/arch/arm64/kvm/emulate-nested.c
    >>> +++ b/arch/arm64/kvm/emulate-nested.c
    >>> @@ -648,15 +648,91 @@ static const struct encoding_to_trap_config encoding_to_cgt[] __initconst = {
    >>> SR_TRAP(SYS_APGAKEYLO_EL1, CGT_HCR_APK),
    >>> SR_TRAP(SYS_APGAKEYHI_EL1, CGT_HCR_APK),
    >>> /* All _EL2 registers */
    >>> - SR_RANGE_TRAP(sys_reg(3, 4, 0, 0, 0),
    >>> - sys_reg(3, 4, 3, 15, 7), CGT_HCR_NV),
    >>> + SR_TRAP(SYS_VPIDR_EL2, CGT_HCR_NV),
    >> I think you miss DBGVCR32_EL2
    > That would be op0 == 10, which I indeed didn't considered given the ranges
    > previously defined. From its pseudocode I see it would make sense only if EL1
    > would support AArch32 but that seems not to be in the plans.
    >
    >>> + SR_TRAP(SYS_VMPIDR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_SCTLR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_ACTLR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_SCTLR2_EL2, CGT_HCR_NV),
    >>> + SR_RANGE_TRAP(SYS_HCR_EL2,
    >>> + SYS_HCRX_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_SMPRIMAP_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_SMCR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_SDER32_EL2, CGT_HCR_NV),
    >>> + SR_RANGE_TRAP(SYS_TTBR0_EL2,
    >>> + SYS_TCR2_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_VTTBR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_VTCR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_VNCR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_VSTTBR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_VSTCR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_DACR32_EL2, CGT_HCR_NV),
    >>> + SR_RANGE_TRAP(SYS_HDFGRTR_EL2,
    >>> + SYS_HAFGRTR_EL2, CGT_HCR_NV),
    >>> /* Skip the SP_EL1 encoding... */
    >>> SR_TRAP(SYS_SPSR_EL2, CGT_HCR_NV),
    >>> SR_TRAP(SYS_ELR_EL2, CGT_HCR_NV),
    >>> - SR_RANGE_TRAP(sys_reg(3, 4, 4, 1, 1),
    >>> - sys_reg(3, 4, 10, 15, 7), CGT_HCR_NV),
    >>> - SR_RANGE_TRAP(sys_reg(3, 4, 12, 0, 0),
    >>> - sys_reg(3, 4, 14, 15, 7), CGT_HCR_NV),
    >>> + /* SPSR_irq, SPSR_abt, SPSR_und, SPSR_fiq */
    >>> + SR_RANGE_TRAP(sys_reg(3, 4, 4, 3, 0),
    >>> + sys_reg(3, 4, 4, 3, 3), CGT_HCR_NV),
    >>> + SR_TRAP(SYS_IFSR32_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_AFSR0_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_AFSR1_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_ESR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_VSESR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_FPEXC32_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_TFSR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_FAR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_HPFAR_EL2, CGT_HCR_NV),
    >> you miss BRBCR_EL2
    > Yes, definitely. Same as above, didn't considered op0 == 10, (Table D18-1).
    > This one seems to me the only one missing too.

    yep
    >
    >>> + SR_TRAP(SYS_PMSCR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_MAIR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_AMAIR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_MPAMHCR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_MPAMVPMV_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_MPAM2_EL2, CGT_HCR_NV),
    >>> + SR_RANGE_TRAP(SYS_MPAMVPM0_EL2,
    >>> + SYS_MPAMVPM7_EL2, CGT_HCR_NV),
    >> About the MPAM where did you find the pseudo code?
    > The pseucode isn't available on the document. I'm following the statement when
    > HCR_EL2.NV is 1, where:
    >
    > "The System or Special-purpose registers for which accesses are trapped and
    > reported using EC syndrome value 0x18 are as follows:
    > — Registers accessed using MRS or MSR with a name ending in _EL2, except, [...]"

    ok thank you for the clarification. With

    BRBCR_EL2 handling, feel free to add my

    Reviewed-by: Eric Auger <eric.auger@redhat.com>

    (I guess you will handle
    DBGVCR32_EL2 in a separate patch)

    Eric

    >
    >>> + /*
    >>> + * Note that the spec. describes a group of MEC registers
    >>> + * whose access should not trap, therefore skip the following:
    >>> + * MECID_A0_EL2, MECID_A1_EL2, MECID_P0_EL2,
    >>> + * MECID_P1_EL2, MECIDR_EL2, VMECID_A_EL2,
    >>> + * VMECID_P_EL2.
    >>> + */
    >>> + SR_RANGE_TRAP(SYS_VBAR_EL2,
    >>> + SYS_RMR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_VDISR_EL2, CGT_HCR_NV),
    >>> + /* ICH_AP0R<m>_EL2 */
    >>> + SR_RANGE_TRAP(SYS_ICH_AP0R0_EL2,
    >>> + SYS_ICH_AP0R3_EL2, CGT_HCR_NV),
    >>> + /* ICH_AP1R<m>_EL2 */
    >>> + SR_RANGE_TRAP(SYS_ICH_AP1R0_EL2,
    >>> + SYS_ICH_AP1R3_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_ICC_SRE_EL2, CGT_HCR_NV),
    >>> + SR_RANGE_TRAP(SYS_ICH_HCR_EL2,
    >>> + SYS_ICH_EISR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_ICH_ELRSR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_ICH_VMCR_EL2, CGT_HCR_NV),
    >>> + /* ICH_LR<m>_EL2 */
    >>> + SR_RANGE_TRAP(SYS_ICH_LR0_EL2,
    >>> + SYS_ICH_LR15_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_CONTEXTIDR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_TPIDR_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_SCXTNUM_EL2, CGT_HCR_NV),
    >>> + /* AMEVCNTVOFF0<n>_EL2, AMEVCNTVOFF1<n>_EL2 */
    >>> + SR_RANGE_TRAP(SYS_AMEVCNTVOFF0n_EL2(0),
    >>> + SYS_AMEVCNTVOFF1n_EL2(15), CGT_HCR_NV),
    >>> + /* CNT*_EL2 */
    >>> + SR_TRAP(SYS_CNTVOFF_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_CNTPOFF_EL2, CGT_HCR_NV),
    >>> + SR_TRAP(SYS_CNTHCTL_EL2, CGT_HCR_NV),
    >>> + SR_RANGE_TRAP(SYS_CNTHP_TVAL_EL2,
    >>> + SYS_CNTHP_CVAL_EL2, CGT_HCR_NV),
    >>> + SR_RANGE_TRAP(SYS_CNTHV_TVAL_EL2,
    >>> + SYS_CNTHV_CVAL_EL2, CGT_HCR_NV),
    >>> + SR_RANGE_TRAP(SYS_CNTHVS_TVAL_EL2,
    >>> + SYS_CNTHVS_CVAL_EL2, CGT_HCR_NV),
    >>> + SR_RANGE_TRAP(SYS_CNTHPS_TVAL_EL2,
    >>> + SYS_CNTHPS_CVAL_EL2, CGT_HCR_NV),
    >>> /* All _EL02, _EL12 registers */
    >>> SR_RANGE_TRAP(sys_reg(3, 5, 0, 0, 0),
    >>> sys_reg(3, 5, 10, 15, 7), CGT_HCR_NV),
    >> Besides this looks good to me and to me this looks safer than the
    >> previous large span approach but that's my taste ;-)
    >>
    > Your suggestions made total sense to me.
    >
    > Thanks!
    > Miguel
    >
    >> Thanks
    >>
    >> Eric
    >

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