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Re: [PATCH] target/ppc/spapr: Update H_GET_CPU_CHARACTERISTICS bits
From: |
David Gibson |
Subject: |
Re: [PATCH] target/ppc/spapr: Update H_GET_CPU_CHARACTERISTICS bits |
Date: |
Tue, 4 May 2021 10:41:12 +1000 |
On Mon, May 03, 2021 at 10:58:33PM +1000, Nicholas Piggin wrote:
> There are several new bits added to the hcall which reflect new issues
> found and new hardware mitigations.
>
> This adds the link stack flush behaviour, link stack flush accelerated
> instruction capability, and several L1D flush type behaviours (which are
> now being specified as negative in order to simplify patched kernel
> compatibility with older firmware).
So, to clarify here, the bits your adding aren't advertising any new
behaviour on qemu/KVM's part, they're just new ways of advertising the
same behaviour?
>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
> hw/ppc/spapr_hcall.c | 5 +++++
> include/hw/ppc/spapr.h | 6 ++++++
> 2 files changed, 11 insertions(+)
>
> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> index 7275d0bba1..f656620232 100644
> --- a/hw/ppc/spapr_hcall.c
> +++ b/hw/ppc/spapr_hcall.c
> @@ -1878,6 +1878,9 @@ static target_ulong
> h_get_cpu_characteristics(PowerPCCPU *cpu,
> behaviour |= H_CPU_BEHAV_L1D_FLUSH_PR;
> break;
> case SPAPR_CAP_FIXED:
> + behaviour |= H_CPU_BEHAV_NO_L1D_FLUSH_ENTRY;
> + behaviour |= H_CPU_BEHAV_NO_L1D_FLUSH_UACCESS;
> + behaviour |= H_CPU_BEHAV_NO_STF_BARRIER;
> break;
> default: /* broken */
> assert(safe_cache == SPAPR_CAP_BROKEN);
> @@ -1909,9 +1912,11 @@ static target_ulong
> h_get_cpu_characteristics(PowerPCCPU *cpu,
> break;
> case SPAPR_CAP_WORKAROUND:
> behaviour |= H_CPU_BEHAV_FLUSH_COUNT_CACHE;
> + behaviour |= H_CPU_BEHAV_FLUSH_LINK_STACK;
> if (count_cache_flush_assist) {
> characteristics |= H_CPU_CHAR_BCCTR_FLUSH_ASSIST;
> }
> + /* Should have a way to enable BCCTR_LINK_FLUSH_ASSIST */
Do we need a new spapr capability for this link flush thing?
> break;
> default: /* broken */
> assert(safe_indirect_branch == SPAPR_CAP_BROKEN);
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 7f40a158f4..883ac1db3c 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -395,10 +395,16 @@ struct SpaprMachineState {
> #define H_CPU_CHAR_THR_RECONF_TRIG PPC_BIT(6)
> #define H_CPU_CHAR_CACHE_COUNT_DIS PPC_BIT(7)
> #define H_CPU_CHAR_BCCTR_FLUSH_ASSIST PPC_BIT(9)
> +#define H_CPU_CHAR_BCCTR_LINK_FLUSH_ASSIST PPC_BIT(11)
> +
> #define H_CPU_BEHAV_FAVOUR_SECURITY PPC_BIT(0)
> #define H_CPU_BEHAV_L1D_FLUSH_PR PPC_BIT(1)
> #define H_CPU_BEHAV_BNDS_CHK_SPEC_BAR PPC_BIT(2)
> #define H_CPU_BEHAV_FLUSH_COUNT_CACHE PPC_BIT(5)
> +#define H_CPU_BEHAV_FLUSH_LINK_STACK PPC_BIT(6)
> +#define H_CPU_BEHAV_NO_L1D_FLUSH_ENTRY PPC_BIT(7)
> +#define H_CPU_BEHAV_NO_L1D_FLUSH_UACCESS PPC_BIT(8)
> +#define H_CPU_BEHAV_NO_STF_BARRIER PPC_BIT(9)
>
> /* Each control block has to be on a 4K boundary */
> #define H_CB_ALIGNMENT 4096
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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