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SubjectRe: [PATCH 2/3] powperc/mm: read TLB Block Invalidate Characteristics
Date
Laurent Dufour <ldufour@linux.ibm.com> writes:

> The PAPR document specifies the TLB Block Invalidate Characteristics which
> is telling which couple base page size / page size is supported by the
> H_BLOCK_REMOVE hcall.
>
> A new set of feature is added to the mmu_psize_def structure to record per
> base page size which page size is supported by H_BLOCK_REMOVE.
>
> A new init service is added to read the characteristics. The size of the
> buffer is set to twice the number of known page size, plus 10 bytes to
> ensure we have enough place.
>
> Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
> ---
> arch/powerpc/include/asm/book3s/64/mmu.h | 3 +
> arch/powerpc/platforms/pseries/lpar.c | 107 +++++++++++++++++++++++
> 2 files changed, 110 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h b/arch/powerpc/include/asm/book3s/64/mmu.h
> index 23b83d3593e2..675895dfe39f 100644
> --- a/arch/powerpc/include/asm/book3s/64/mmu.h
> +++ b/arch/powerpc/include/asm/book3s/64/mmu.h
> @@ -12,11 +12,14 @@
> * sllp : is a bit mask with the value of SLB L || LP to be or'ed
> * directly to a slbmte "vsid" value
> * penc : is the HPTE encoding mask for the "LP" field:
> + * hblk : H_BLOCK_REMOVE supported block size for this page size in
> + * segment who's base page size is that page size.
> *
> */
> struct mmu_psize_def {
> unsigned int shift; /* number of bits */
> int penc[MMU_PAGE_COUNT]; /* HPTE encoding */
> + int hblk[MMU_PAGE_COUNT]; /* H_BLOCK_REMOVE support */
> unsigned int tlbiel; /* tlbiel supported for that page size */
> unsigned long avpnm; /* bits to mask out in AVPN in the HPTE */
> union {
> diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
> index 4f76e5f30c97..375e19b3cf53 100644
> --- a/arch/powerpc/platforms/pseries/lpar.c
> +++ b/arch/powerpc/platforms/pseries/lpar.c
> @@ -1311,6 +1311,113 @@ static void do_block_remove(unsigned long number, struct ppc64_tlb_batch *batch,
> (void)call_block_remove(pix, param, true);
> }
>
> +static inline void __init set_hblk_bloc_size(int bpsize, int psize,
> + unsigned int block_size)
> +{
> + struct mmu_psize_def *def = &mmu_psize_defs[bpsize];
> +
> + if (block_size > def->hblk[psize])
> + def->hblk[psize] = block_size;
> +}
> +
> +static inline void __init check_lp_set_hblk(unsigned int lp,
> + unsigned int block_size)
> +{
> + unsigned int bpsize, psize;
> +
> +
> + /* First, check the L bit, if not set, this means 4K */
> + if ((lp & 0x80) == 0) {
> + set_hblk_bloc_size(MMU_PAGE_4K, MMU_PAGE_4K, block_size);
> + return;
> + }
> +
> + /* PAPR says to look at bits 2-7 (0 = MSB) */
> + lp &= 0x3f;
> + for (bpsize = 0; bpsize < MMU_PAGE_COUNT; bpsize++) {
> + struct mmu_psize_def *def = &mmu_psize_defs[bpsize];
> +
> + for (psize = 0; psize < MMU_PAGE_COUNT; psize++) {
> + if (def->penc[psize] == lp) {
> + set_hblk_bloc_size(bpsize, psize, block_size);
> + return;
> + }
> + }
> + }
> +}
> +
> +#define SPLPAR_TLB_BIC_TOKEN 50
> +#define SPLPAR_TLB_BIC_MAXLENGTH (MMU_PAGE_COUNT*2 + 10)
> +static int __init read_tlbbi_characteristics(void)
> +{
> + int call_status;
> + unsigned char local_buffer[SPLPAR_TLB_BIC_MAXLENGTH];
> + int len, idx, bpsize;
> +
> + if (!firmware_has_feature(FW_FEATURE_BLOCK_REMOVE)) {
> + pr_info("H_BLOCK_REMOVE is not supported");
> + return 0;
> + }
> +
> + memset(local_buffer, 0, SPLPAR_TLB_BIC_MAXLENGTH);
> +
> + spin_lock(&rtas_data_buf_lock);
> + memset(rtas_data_buf, 0, RTAS_DATA_BUF_SIZE);
> + call_status = rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,
> + NULL,
> + SPLPAR_TLB_BIC_TOKEN,
> + __pa(rtas_data_buf),
> + RTAS_DATA_BUF_SIZE);
> + memcpy(local_buffer, rtas_data_buf, SPLPAR_TLB_BIC_MAXLENGTH);
> + local_buffer[SPLPAR_TLB_BIC_MAXLENGTH - 1] = '\0';
> + spin_unlock(&rtas_data_buf_lock);
> +
> + if (call_status != 0) {
> + pr_warn("%s %s Error calling get-system-parameter (0x%x)\n",
> + __FILE__, __func__, call_status);
> + return 0;
> + }
> +
> + /*
> + * The first two (2) bytes of the data in the buffer are the length of
> + * the returned data, not counting these first two (2) bytes.
> + */
> + len = local_buffer[0] * 256 + local_buffer[1] + 2;
> + if (len >= SPLPAR_TLB_BIC_MAXLENGTH) {
> + pr_warn("%s too large returned buffer %d", __func__, len);
> + return 0;
> + }
> +
> + idx = 2;
> + while (idx < len) {
> + unsigned int block_size = local_buffer[idx++];
> + unsigned int npsize;
> +
> + if (!block_size)
> + break;
> +
> + block_size = 1 << block_size;
> + if (block_size != 8)
> + /* We only support 8 bytes size TLB invalidate buffer */
> + pr_warn("Unsupported H_BLOCK_REMOVE block size : %d\n",
> + block_size);

Should we skip setting block size if we find block_size != 8? Also can
we avoid doing that pr_warn in loop and only warn if we don't find
block_size 8 in the invalidate characteristics array?

> +
> + for (npsize = local_buffer[idx++]; npsize > 0; npsize--)
> + check_lp_set_hblk((unsigned int) local_buffer[idx++],
> + block_size);
> + }
> +
> + for (bpsize = 0; bpsize < MMU_PAGE_COUNT; bpsize++)
> + for (idx = 0; idx < MMU_PAGE_COUNT; idx++)
> + if (mmu_psize_defs[bpsize].hblk[idx])
> + pr_info("H_BLOCK_REMOVE supports base psize:%d psize:%d block size:%d",
> + bpsize, idx,
> + mmu_psize_defs[bpsize].hblk[idx]);
> +
> + return 0;
> +}
> +machine_arch_initcall(pseries, read_tlbbi_characteristics);
> +
> /*
> * Take a spinlock around flushes to avoid bouncing the hypervisor tlbie
> * lock.
> --
> 2.23.0

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