[PATCH v4 09/16] powerpc/pseries/vas: Add HCALL wrappers for VAS handling
Michael Ellerman
mpe at ellerman.id.au
Fri Jun 4 21:52:38 AEST 2021
Haren Myneni <haren at linux.ibm.com> writes:
> This patch adds the following HCALL wrapper functions to allocate,
Normal spelling is "hcall".
> modify and deallocate VAS windows, and retrieve VAS capabilities.
>
> H_ALLOCATE_VAS_WINDOW: Allocate VAS window
> H_DEALLOCATE_VAS_WINDOW: Close VAS window
> H_MODIFY_VAS_WINDOW: Setup window before using
> H_QUERY_VAS_CAPABILITIES: Get VAS capabilities
Please tell us which version of PAPR, and in which section etc., these
are described in.
> Signed-off-by: Haren Myneni <haren at linux.ibm.com>
> Reviewed-by: Nicholas Piggin <npiggin at gmail.com>
> ---
> arch/powerpc/platforms/pseries/vas.c | 217 +++++++++++++++++++++++++++
> 1 file changed, 217 insertions(+)
> create mode 100644 arch/powerpc/platforms/pseries/vas.c
>
> diff --git a/arch/powerpc/platforms/pseries/vas.c b/arch/powerpc/platforms/pseries/vas.c
> new file mode 100644
> index 000000000000..06960151477c
> --- /dev/null
> +++ b/arch/powerpc/platforms/pseries/vas.c
> @@ -0,0 +1,217 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright 2020-21 IBM Corp.
> + */
> +
> +#define pr_fmt(fmt) "vas: " fmt
> +
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/export.h>
> +#include <linux/types.h>
> +#include <linux/delay.h>
> +#include <linux/slab.h>
> +#include <linux/irqdomain.h>
> +#include <linux/interrupt.h>
> +#include <linux/sched/mm.h>
> +#include <linux/mmu_context.h>
> +#include <asm/hvcall.h>
> +#include <asm/hvconsole.h>
> +#include <asm/machdep.h>
Do we need all those headers?
> +#include <asm/plpar_wrappers.h>
> +#include <asm/vas.h>
> +#include "vas.h"
> +
> +#define VAS_INVALID_WIN_ADDRESS 0xFFFFFFFFFFFFFFFFul
> +#define VAS_DEFAULT_DOMAIN_ID 0xFFFFFFFFFFFFFFFFul
Some blank lines for formatting please.
> +/* Authority Mask Register (AMR) value is not supported in */
> +/* linux implementation. So pass '0' to modify window HCALL */
Please fix the comment formatting.
> +#define VAS_AMR_VALUE 0
This is only used in one place. It'd be simpler to just pass 0 and move
the comment there.
> +/* phyp allows one credit per window right now */
> +#define DEF_WIN_CREDS 1
> +
> +static int64_t hcall_return_busy_check(int64_t rc)
> +{
Please use normal kernel types, ie. s64, or just long.
Same comment throughout.
> + /* Check if we are stalled for some time */
> + if (H_IS_LONG_BUSY(rc)) {
> + msleep(get_longbusy_msecs(rc));
> + rc = H_BUSY;
> + } else if (rc == H_BUSY) {
> + cond_resched();
> + }
> +
> + return rc;
> +}
> +
> +/*
> + * Allocate VAS window HCALL
> + */
> +static int plpar_vas_allocate_window(struct vas_window *win, u64 *domain,
> + u8 wintype, u16 credits)
You don't have to use the "plpar" prefix for these sort of wrappers.
Just naming them after the hcall would probably be clearer, so:
h_allocate_vas_window(... )
> +{
> + long retbuf[PLPAR_HCALL9_BUFSIZE] = {0};
> + int64_t rc;
> +
> + do {
> + rc = plpar_hcall9(H_ALLOCATE_VAS_WINDOW, retbuf, wintype,
> + credits, domain[0], domain[1], domain[2],
> + domain[3], domain[4], domain[5]);
> +
> + rc = hcall_return_busy_check(rc);
> + } while (rc == H_BUSY);
> +
> + switch (rc) {
> + case H_SUCCESS:
> + win->winid = retbuf[0];
> + win->lpar.win_addr = retbuf[1];
> + win->lpar.complete_irq = retbuf[2];
> + win->lpar.fault_irq = retbuf[3];
You shouldn't mutate win until you know there is no error.
> + if (win->lpar.win_addr == VAS_INVALID_WIN_ADDRESS) {
> + pr_err("HCALL(%x): COPY/PASTE is not supported\n",
> + H_ALLOCATE_VAS_WINDOW);
> + return -ENOTSUPP;
> + }
> + return 0;
> + case H_PARAMETER:
> + pr_err("HCALL(%x): Invalid window type (%u)\n",
> + H_ALLOCATE_VAS_WINDOW, wintype);
> + return -EINVAL;
> + case H_P2:
> + pr_err("HCALL(%x): Credits(%u) exceed maximum window credits\n",
> + H_ALLOCATE_VAS_WINDOW, credits);
> + return -EINVAL;
> + case H_COP_HW:
> + pr_err("HCALL(%x): User-mode COPY/PASTE is not supported\n",
> + H_ALLOCATE_VAS_WINDOW);
> + return -ENOTSUPP;
> + case H_RESOURCE:
> + pr_err("HCALL(%x): LPAR credit limit exceeds window limit\n",
> + H_ALLOCATE_VAS_WINDOW);
> + return -EPERM;
> + case H_CONSTRAINED:
> + pr_err("HCALL(%x): Credits (%u) are not available\n",
> + H_ALLOCATE_VAS_WINDOW, credits);
> + return -EPERM;
> + default:
> + pr_err("HCALL(%x): Unexpected error %lld\n",
> + H_ALLOCATE_VAS_WINDOW, rc);
> + return -EIO;
> + }
Do we really need all these error prints? It's very verbose, and
presumably in normal operation none of these are meant to happen anyway.
Can't we just have a single case that prints the error value?
Same comment for the other hcalls.
> +}
> +
> +/*
> + * Deallocate VAS window HCALL.
> + */
> +static int plpar_vas_deallocate_window(u64 winid)
> +{
> + int64_t rc;
> +
> + do {
> + rc = plpar_hcall_norets(H_DEALLOCATE_VAS_WINDOW, winid);
> +
> + rc = hcall_return_busy_check(rc);
> + } while (rc == H_BUSY);
> +
> + switch (rc) {
> + case H_SUCCESS:
> + return 0;
> + case H_PARAMETER:
> + pr_err("HCALL(%x): Invalid window ID %llu\n",
> + H_DEALLOCATE_VAS_WINDOW, winid);
> + return -EINVAL;
> + case H_STATE:
> + pr_err("HCALL(%x): Window(%llu): Invalid page table entries\n",
> + H_DEALLOCATE_VAS_WINDOW, winid);
> + return -EPERM;
> + default:
> + pr_err("HCALL(%x): Unexpected error %lld for window(%llu)\n",
> + H_DEALLOCATE_VAS_WINDOW, rc, winid);
> + return -EIO;
> + }
> +}
> +
> +/*
> + * Modify VAS window.
> + * After the window is opened with allocate window HCALL, configure it
> + * with flags and LPAR PID before using.
> + */
> +static int plpar_vas_modify_window(struct vas_window *win)
> +{
> + int64_t rc;
> + u32 lpid = mfspr(SPRN_PID);
The lpid would be SPRN_LPID ?
But you can't read it from a guest. Is the variable just misnamed?
> +
> + /*
> + * AMR value is not supported in Linux implementation
> + * phyp ignores it if 0 is passed.
> + */
Heh, this comment is already here.
Do you mean the Linux VAS implementation doesn't support AMR? Because
Linux definitely does use AMR.
> + do {
> + rc = plpar_hcall_norets(H_MODIFY_VAS_WINDOW, win->winid,
> + lpid, 0, VAS_MOD_WIN_FLAGS,
> + VAS_AMR_VALUE);
> +
> + rc = hcall_return_busy_check(rc);
> + } while (rc == H_BUSY);
> +
> + switch (rc) {
> + case H_SUCCESS:
> + return 0;
> + case H_PARAMETER:
> + pr_err("HCALL(%x): Invalid window ID %u\n",
> + H_MODIFY_VAS_WINDOW, win->winid);
> + return -EINVAL;
> + case H_P2:
> + pr_err("HCALL(%x): Window(%d): Invalid LPAR Process ID %u\n",
> + H_MODIFY_VAS_WINDOW, lpid, win->winid);
> + return -EINVAL;
> + case H_P3:
> + /* LPAR thread ID is deprecated on P10 */
> + pr_err("HCALL(%x): Invalid LPAR Thread ID for window(%u)\n",
> + H_MODIFY_VAS_WINDOW, win->winid);
> + return -EINVAL;
> + case H_STATE:
> + pr_err("HCALL(%x): Jobs in progress, Can't modify window(%u)\n",
> + H_MODIFY_VAS_WINDOW, win->winid);
> + return -EBUSY;
> + default:
> + pr_err("HCALL(%x): Unexpected error %lld for window(%u)\n",
> + H_MODIFY_VAS_WINDOW, rc, win->winid);
> + return -EIO;
> + }
> +}
> +
> +/*
> + * This HCALL is used to determine the capabilities that pHyp provides.
> + * @hcall: H_QUERY_VAS_CAPABILITIES or H_QUERY_NX_CAPABILITIES
> + * @query_type: If 0 is passed, phyp returns the overall capabilities
> + * which provides all feature(s) that are available. Then
> + * query phyp to get the corresponding capabilities for
> + * the specific feature.
> + * Example: H_QUERY_VAS_CAPABILITIES provides VAS GZIP QoS
> + * and VAS GZIP Default capabilities.
> + * H_QUERY_NX_CAPABILITIES provides NX GZIP
> + * capabilities.
> + * @result: Return buffer to save capabilities.
> + */
> +int plpar_vas_query_capabilities(const u64 hcall, u8 query_type,
> + u64 result)
> +{
> + int64_t rc;
> +
> + rc = plpar_hcall_norets(hcall, query_type, result);
> +
> + switch (rc) {
> + case H_SUCCESS:
> + return 0;
> + case H_PARAMETER:
> + pr_err("HCALL(%llx): Invalid query type %u\n", hcall,
> + query_type);
> + return -EINVAL;
> + case H_PRIVILEGE:
> + pr_err("HCALL(%llx): Invalid result buffer 0x%llx\n",
> + hcall, result);
> + return -EACCES;
> + default:
> + pr_err("HCALL(%llx): Unexpected error %lld\n", hcall, rc);
> + return -EIO;
> + }
> +}
cheers
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