[PATCH v1 2/8] ACPI: ASPT: Add helper to parse table

Jeremi Piotrowski
2023-01-23T15:24:34Z

The ASP table indicates the presence of a Platform Security Processor
with a register window and registers to configure interrupt delivery.
The helper checks for the presence of the table and returns a resource
and struct with register offsets.

Signed-off-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
---
drivers/acpi/Makefile | 1 +
drivers/acpi/aspt.c | 104 ++++++++++++++++++++++++++++++
include/linux/platform_data/psp.h | 32 +++++++++
3 files changed, 137 insertions(+)
create mode 100644 drivers/acpi/aspt.c
create mode 100644 include/linux/platform_data/psp.h

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 0002eecbf870..9621c90e0221 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -57,6 +57,7 @@ acpi-y += evged.o
acpi-y += sysfs.o
acpi-y += property.o
acpi-$(CONFIG_X86) += acpi_cmos_rtc.o
+acpi-$(CONFIG_X86) += aspt.o
acpi-$(CONFIG_X86) += x86/apple.o
acpi-$(CONFIG_X86) += x86/utils.o
acpi-$(CONFIG_X86) += x86/s2idle.o
diff --git a/drivers/acpi/aspt.c b/drivers/acpi/aspt.c
new file mode 100644
index 000000000000..cf629db35036
--- /dev/null
+++ b/drivers/acpi/aspt.c
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#define pr_fmt(fmt) "ACPI: ASPT: " fmt
+#include <linux/acpi.h>
+#include <linux/kernel.h>
+#include <linux/platform_data/psp.h>
+
+static int __init psp_validate_regs(const struct acpi_aspt_global_regs *gregs,
+ const struct acpi_aspt_sev_mbox_regs *sevregs,
+ const struct acpi_aspt_acpi_mbox_regs *acpiregs)
+{
+ u64 pfn;
+ int idx;
+ u64 regs[] = {
+ gregs->feature_reg_addr,
+ gregs->irq_en_reg_addr,
+ gregs->irq_st_reg_addr,
+ sevregs->cmd_resp_reg_addr,
+ sevregs->cmd_buf_lo_reg_addr,
+ sevregs->cmd_buf_hi_reg_addr,
+ acpiregs->cmd_resp_reg_addr
+ };
+ pfn = regs[0] >> PAGE_SHIFT;
+ for (idx = 1; idx < ARRAY_SIZE(regs); idx++) {
+ if (regs[idx] >> PAGE_SHIFT != pfn)
+ return -EINVAL;
+ }
+ return 0;
+}
+
+/**
+ * acpi_parse_aspt - Parse ASPT table and return contained information
+ * @res: will be filled with the address and size of the ASP register window
+ * @pdata: will be filled with the register offsets parsed from the ASPT table
+ */
+int __init acpi_parse_aspt(struct resource *res, struct psp_platform_data *pdata)
+{
+ struct acpi_aspt_acpi_mbox_regs acpiregs = {};
+ struct acpi_aspt_sev_mbox_regs sevregs = {};
+ struct acpi_aspt_global_regs gregs = {};
+ struct acpi_aspt_header *entry, *end;
+ struct acpi_table_aspt *aspt;
+ unsigned long base;
+ acpi_status status;
+ int err = 0;
+
+ status = acpi_get_table(ACPI_SIG_ASPT, 0, (struct acpi_table_header **)&aspt);
+ if (ACPI_FAILURE(status))
+ return -ENODEV;
+ if (aspt->header.revision != ASPT_REVISION_ID) {
+ pr_err("unsupported table revision: %d\n", (int)aspt->header.revision);
+ err = -ENODEV;
+ goto exit;
+ }
+ entry = (struct acpi_aspt_header *)(aspt + 1);
+ end = (struct acpi_aspt_header *)((void *)aspt + aspt->header.length);
+ while (entry < end) {
+ if (((void *)entry + entry->length) > (void *)end) {
+ pr_err("error during parsing\n");
+ err = -EINVAL;
+ goto exit;
+ }
+ switch (entry->type) {
+ case ACPI_ASPT_TYPE_GLOBAL_REGS:
+ memcpy(&gregs, entry, entry->length);
+ break;
+ case ACPI_ASPT_TYPE_SEV_MBOX_REGS:
+ memcpy(&sevregs, entry, entry->length);
+ break;
+ case ACPI_ASPT_TYPE_ACPI_MBOX_REGS:
+ memcpy(&acpiregs, entry, entry->length);
+ break;
+ }
+ entry = (struct acpi_aspt_header *)((void *)entry + entry->length);
+ }
+ if (!gregs.header.length || !sevregs.header.length || !acpiregs.header.length) {
+ pr_err("missing ASPT table entry: %u %u %u\n", gregs.header.length,
+ sevregs.header.length,
+ acpiregs.header.length);
+ err = -EINVAL;
+ goto exit;
+ }
+ /* All registers are expected to be within the same page */
+ err = psp_validate_regs(&gregs, &sevregs, &acpiregs);
+ if (err) {
+ pr_err("ASPT registers span multiple pages\n");
+ goto exit;
+ }
+
+ base = ALIGN_DOWN(gregs.feature_reg_addr, PAGE_SIZE);
+ *res = (struct resource)DEFINE_RES_MEM(base, PAGE_SIZE);
+
+ pdata->sev_cmd_resp_reg = sevregs.cmd_resp_reg_addr & ~PAGE_MASK;
+ pdata->sev_cmd_buf_lo_reg = sevregs.cmd_buf_lo_reg_addr & ~PAGE_MASK;
+ pdata->sev_cmd_buf_hi_reg = sevregs.cmd_buf_hi_reg_addr & ~PAGE_MASK;
+ pdata->feature_reg = gregs.feature_reg_addr & ~PAGE_MASK;
+ pdata->irq_en_reg = gregs.irq_en_reg_addr & ~PAGE_MASK;
+ pdata->irq_st_reg = gregs.irq_st_reg_addr & ~PAGE_MASK;
+ pdata->mbox_irq_id = sevregs.mbox_irq_id;
+ pdata->acpi_cmd_resp_reg = acpiregs.cmd_resp_reg_addr & ~PAGE_MASK;
+
+exit:
+ acpi_put_table((struct acpi_table_header *)aspt);
+ return err;
+}
diff --git a/include/linux/platform_data/psp.h b/include/linux/platform_data/psp.h
new file mode 100644
index 000000000000..b761f72168d6
--- /dev/null
+++ b/include/linux/platform_data/psp.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * psp.h - PSP register offsets parsed from ASPT ACPI table
+ */
+
+#ifndef __LINUX_PSP_H
+#define __LINUX_PSP_H
+
+#include <linux/types.h>
+#include <linux/ioport.h>
+
+struct psp_platform_data {
+ int sev_cmd_resp_reg;
+ int sev_cmd_buf_lo_reg;
+ int sev_cmd_buf_hi_reg;
+ int feature_reg;
+ int irq_en_reg;
+ int irq_st_reg;
+ int mbox_irq_id;
+ int acpi_cmd_resp_reg;
+};
+
+#if IS_ENABLED(CONFIG_ACPI)
+int acpi_parse_aspt(struct resource *res, struct psp_platform_data *pdata);
+#else
+static inline acpi_parse_aspt(struct resource *res, struct psp_platform_data *pdata)
+{
+ return -ENODEV;
+}
+#endif
+
+#endif /* __LINUX_PSP_H */
--
2.25.1