On Wed, Feb 10, 2016 at 07:09:12PM +0100, Thomas Huth wrote: > This hypercall either initializes a page with zeros, or copies > another page. > According to LoPAPR, the i-cache of the page should also be > flushed when using H_ICACHE_INVALIDATE or H_ICACHE_SYNCHRONIZE, > but this is currently only done when running with TCG - assuming > the cache will be flushed with KVM anyway when switching back to > kernel / VM context.
I don't think that's true. dcache and icache aren't usually flushed
by kernel/user or even process context changes in Linux. Cache
control instructions aren't priveleged so, I think to get this right
you'd need a helper which does dcbst and icbi across the page.
I'm pretty sure libc needs to do this at several points, but alas I
don't think there's an exported function to do it.
> The code currently also does not explicitely flush the data cache
> with H_ICACHE_SYNCHRONIZE, since this either also should be done
> when switching back to kernel / VM context (with KVM), or not matter
> anyway (for TCG).
>
> Signed-off-by: Thomas Huth <th...@redhat.com>
> ---
> hw/ppc/spapr_hcall.c | 42 ++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 42 insertions(+)
>
> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> index f14f849..91e703d 100644
> --- a/hw/ppc/spapr_hcall.c
> +++ b/hw/ppc/spapr_hcall.c
> @@ -387,6 +387,47 @@ static target_ulong h_set_xdabr(PowerPCCPU *cpu,
> sPAPRMachineState *spapr,
> return H_SUCCESS;
> }
>
> +static target_ulong h_page_init(PowerPCCPU *cpu, sPAPRMachineState *spapr,
> + target_ulong opcode, target_ulong *args)
> +{
> + target_ulong flags = args[0];
> + target_ulong dest = args[1];
> + target_ulong src = args[2];
> + uint8_t buf[TARGET_PAGE_SIZE];
> +
> + if (flags & ~(H_ICACHE_SYNCHRONIZE | H_ICACHE_INVALIDATE
> + | H_COPY_PAGE | H_ZERO_PAGE)) {
> + qemu_log_mask(LOG_UNIMP, "h_page_init: Bad flags (" TARGET_FMT_lx
> "\n",
> + flags);
This should return H_PARAMETER as well as logging, surely?
> + }
> +
> + if (!is_ram_address(spapr, dest) || (dest & ~TARGET_PAGE_MASK) != 0) {
> + return H_PARAMETER;
> + }
> +
> + if (flags & H_COPY_PAGE) {
> + if (!is_ram_address(spapr, src) || (src & ~TARGET_PAGE_MASK) != 0) {
> + return H_PARAMETER;
> + }
> + cpu_physical_memory_read(src, buf, TARGET_PAGE_SIZE);
> + } else if (flags & H_ZERO_PAGE) {
> + memset(buf, 0, TARGET_PAGE_SIZE);
> + }
> +
> + if (flags & (H_COPY_PAGE | H_ZERO_PAGE)) {
> + cpu_physical_memory_write(dest, buf, TARGET_PAGE_SIZE);
> + }
Hmm, so this does 2 copies for an H_COPY_PAGE and a zero and a copy
for H_ZERO_PAGE, which is going to be substantially slower than the
caller might expect.
> + if (flags & (H_ICACHE_SYNCHRONIZE | H_ICACHE_INVALIDATE)) {
> + if (tcg_enabled()) {
> + tb_flush(CPU(cpu));
> + }
> + /* XXX: Flush data cache for H_ICACHE_SYNCHRONIZE? */
> + }
> +
> + return H_SUCCESS;
> +}
> +
> #define FLAGS_REGISTER_VPA 0x0000200000000000ULL
> #define FLAGS_REGISTER_DTL 0x0000400000000000ULL
> #define FLAGS_REGISTER_SLBSHADOW 0x0000600000000000ULL
> @@ -1046,6 +1087,7 @@ static void hypercall_register_types(void)
> spapr_register_hypercall(H_SET_SPRG0, h_set_sprg0);
> spapr_register_hypercall(H_SET_DABR, h_set_dabr);
> spapr_register_hypercall(H_SET_XDABR, h_set_xdabr);
> + spapr_register_hypercall(H_PAGE_INIT, h_page_init);
> spapr_register_hypercall(H_SET_MODE, h_set_mode);
>
> /* "debugger" hcalls (also used by SLOF). Note: We do -not- differenciate
--
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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