powerpc/pseries/vas: Add hcall wrappers for VAS handling

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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/40fb02a4d56ca4e240b074a15029082055be5997.camel@linux.ibm.com

arch/powerpc/platforms/pseries/vas.c

+// 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 <asm/hvcall.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
+/* The hypervisor allows one credit per window right now */
+#define DEF_WIN_CREDS		1
+
+static long hcall_return_busy_check(long 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 h_allocate_vas_window(struct pseries_vas_window *win, u64 *domain,
+				     u8 wintype, u16 credits)
+{
+	long retbuf[PLPAR_HCALL9_BUFSIZE] = {0};
+	long 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);
+
+	if (rc == H_SUCCESS) {
+		if (win->win_addr == VAS_INVALID_WIN_ADDRESS) {
+			pr_err("H_ALLOCATE_VAS_WINDOW: COPY/PASTE is not supported\n");
+			return -ENOTSUPP;
+		}
+		win->vas_win.winid = retbuf[0];
+		win->win_addr = retbuf[1];
+		win->complete_irq = retbuf[2];
+		win->fault_irq = retbuf[3];
+		return 0;
+	}
+
+	pr_err("H_ALLOCATE_VAS_WINDOW error: %ld, wintype: %u, credits: %u\n",
+		rc, wintype, credits);
+
+	return -EIO;
+}
+
+/*
+ * Deallocate VAS window hcall.
+ */
+static int h_deallocate_vas_window(u64 winid)
+{
+	long rc;
+
+	do {
+		rc = plpar_hcall_norets(H_DEALLOCATE_VAS_WINDOW, winid);
+
+		rc = hcall_return_busy_check(rc);
+	} while (rc == H_BUSY);
+
+	if (rc == H_SUCCESS)
+		return 0;
+
+	pr_err("H_DEALLOCATE_VAS_WINDOW error: %ld, winid: %llu\n",
+		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 h_modify_vas_window(struct pseries_vas_window *win)
+{
+	long rc;
+	u32 lpid = mfspr(SPRN_PID);
+
+	/*
+	 * AMR value is not supported in Linux VAS implementation.
+	 * The hypervisor ignores it if 0 is passed.
+	 */
+	do {
+		rc = plpar_hcall_norets(H_MODIFY_VAS_WINDOW,
+					win->vas_win.winid, lpid, 0,
+					VAS_MOD_WIN_FLAGS, 0);
+
+		rc = hcall_return_busy_check(rc);
+	} while (rc == H_BUSY);
+
+	if (rc == H_SUCCESS)
+		return 0;
+
+	pr_err("H_MODIFY_VAS_WINDOW error: %ld, winid %u lpid %u\n",
+			rc, win->vas_win.winid, lpid);
+	return -EIO;
+}
+
+/*
+ * This hcall is used to determine the capabilities from the hypervisor.
+ * @hcall: H_QUERY_VAS_CAPABILITIES or H_QUERY_NX_CAPABILITIES
+ * @query_type: If 0 is passed, the hypervisor returns the overall
+ *		capabilities which provides all feature(s) that are
+ *		available. Then query the hypervisor 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 h_query_vas_capabilities(const u64 hcall, u8 query_type, u64 result)
+{
+	long rc;
+
+	rc = plpar_hcall_norets(hcall, query_type, result);
+
+	if (rc == H_SUCCESS)
+		return 0;
+
+	pr_err("HCALL(%llx) error %ld, query_type %u, result buffer 0x%llx\n",
+			hcall, rc, query_type, result);
+	return -EIO;
+}