[PATCH v4 09/16] powerpc/pseries/vas: Add HCALL wrappers for VAS handling

[Haren Myneni <haren@linux.ibm.com>]

This patch adds the following HCALL wrapper functions to allocate,
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

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@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>
+#include <asm/plpar_wrappers.h>
+#include <asm/vas.h>
+#include "vas.h"
+
+#define	VAS_INVALID_WIN_ADDRESS	0xFFFFFFFFFFFFFFFFul
+#define	VAS_DEFAULT_DOMAIN_ID	0xFFFFFFFFFFFFFFFFul
+/* Authority Mask Register (AMR) value is not supported in */
+/* linux implementation. So pass '0' to modify window HCALL */
+#define	VAS_AMR_VALUE	0
+/* phyp allows one credit per window right now */
+#define DEF_WIN_CREDS		1
+
+static int64_t hcall_return_busy_check(int64_t rc)
+{
+	/* 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)
+{
+	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];
+		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;
+	}
+}
+
+/*
+ * 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);
+
+	/*
+	 * AMR value is not supported in Linux implementation
+	 * phyp ignores it if 0 is passed.
+	 */
+	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;
+	}
+}
-- 
2.18.2