[RFC PATCH 03/12] powerpc/prom_init: Add the ESM call to prom_init

Thiago Jung Bauermann
2019-05-21T04:51:55Z

From: Ram Pai <linuxram@us.ibm.com>

Make the Enter-Secure-Mode (ESM) ultravisor call to switch the VM to secure
mode. Add "svm=" command line option to turn off switching to secure mode.
Introduce CONFIG_PPC_SVM to control support for secure guests.

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
[ Generate an RTAS os-term hcall when the ESM ucall fails. ]
Signed-off-by: Michael Anderson <andmike@linux.ibm.com>
[ Cleaned up the code a bit. ]
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
---
.../admin-guide/kernel-parameters.txt | 5 +
arch/powerpc/include/asm/ultravisor-api.h | 1 +
arch/powerpc/kernel/prom_init.c | 124 ++++++++++++++++++
3 files changed, 130 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index c45a19d654f3..7237d86b25c6 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4501,6 +4501,11 @@
/sys/power/pm_test). Only available when CONFIG_PM_DEBUG
is set. Default value is 5.

+ svm= [PPC]
+ Format: { on | off | y | n | 1 | 0 }
+ This parameter controls use of the Protected
+ Execution Facility on pSeries.
+
swapaccount=[0|1]
[KNL] Enable accounting of swap in memory resource
controller if no parameter or 1 is given or disable
diff --git a/arch/powerpc/include/asm/ultravisor-api.h b/arch/powerpc/include/asm/ultravisor-api.h
index 15e6ce77a131..0e8b72081718 100644
--- a/arch/powerpc/include/asm/ultravisor-api.h
+++ b/arch/powerpc/include/asm/ultravisor-api.h
@@ -19,6 +19,7 @@

/* opcodes */
#define UV_WRITE_PATE 0xF104
+#define UV_ESM 0xF110
#define UV_RETURN 0xF11C

#endif /* _ASM_POWERPC_ULTRAVISOR_API_H */
diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index 523bb99d7676..5d8a3efb54f2 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -44,6 +44,7 @@
#include <asm/sections.h>
#include <asm/machdep.h>
#include <asm/asm-prototypes.h>
+#include <asm/ultravisor-api.h>

#include <linux/linux_logo.h>

@@ -174,6 +175,10 @@ static unsigned long __prombss prom_tce_alloc_end;
static bool __prombss prom_radix_disable;
#endif

+#ifdef CONFIG_PPC_SVM
+static bool __prombss prom_svm_disable;
+#endif
+
struct platform_support {
bool hash_mmu;
bool radix_mmu;
@@ -809,6 +814,17 @@ static void __init early_cmdline_parse(void)
if (prom_radix_disable)
prom_debug("Radix disabled from cmdline\n");
#endif /* CONFIG_PPC_PSERIES */
+
+#ifdef CONFIG_PPC_SVM
+ opt = prom_strstr(prom_cmd_line, "svm=");
+ if (opt) {
+ bool val;
+
+ opt += sizeof("svm=") - 1;
+ if (!prom_strtobool(opt, &val))
+ prom_svm_disable = !val;
+ }
+#endif /* CONFIG_PPC_SVM */
}

#ifdef CONFIG_PPC_PSERIES
@@ -1707,6 +1723,43 @@ static void __init prom_close_stdin(void)
}
}

+#ifdef CONFIG_PPC_SVM
+static int prom_rtas_os_term_hcall(uint64_t args)
+{
+ register uint64_t arg1 asm("r3") = 0xf000;
+ register uint64_t arg2 asm("r4") = args;
+
+ asm volatile("sc 1\n" : "=r" (arg1) :
+ "r" (arg1),
+ "r" (arg2) :);
+ return arg1;
+}
+
+static struct rtas_args __prombss os_term_args;
+
+static void __init prom_rtas_os_term(char *str)
+{
+ phandle rtas_node;
+ __be32 val;
+ u32 token;
+
+ prom_printf("%s: start...\n", __func__);
+ rtas_node = call_prom("finddevice", 1, 1, ADDR("/rtas"));
+ prom_printf("rtas_node: %x\n", rtas_node);
+ if (!PHANDLE_VALID(rtas_node))
+ return;
+
+ val = 0;
+ prom_getprop(rtas_node, "ibm,os-term", &val, sizeof(val));
+ token = be32_to_cpu(val);
+ prom_printf("ibm,os-term: %x\n", token);
+ if (token == 0)
+ prom_panic("Could not get token for ibm,os-term\n");
+ os_term_args.token = cpu_to_be32(token);
+ prom_rtas_os_term_hcall((uint64_t)&os_term_args);
+}
+#endif /* CONFIG_PPC_SVM */
+
/*
* Allocate room for and instantiate RTAS
*/
@@ -3162,6 +3215,74 @@ static void unreloc_toc(void)
#endif
#endif

+#ifdef CONFIG_PPC_SVM
+/*
+ * The ESM blob is a data structure with information needed by the Ultravisor to
+ * validate the integrity of the secure guest.
+ */
+static void *get_esm_blob(void)
+{
+ /*
+ * FIXME: We are still finalizing the details on how prom_init will grab
+ * the ESM blob. When that is done, this function will be updated.
+ */
+ return (void *)0xdeadbeef;
+}
+
+/*
+ * Perform the Enter Secure Mode ultracall.
+ */
+static int enter_secure_mode(void *esm_blob, void *retaddr, void *fdt)
+{
+ register uint64_t func asm("r0") = UV_ESM;
+ register uint64_t arg1 asm("r3") = (uint64_t)esm_blob;
+ register uint64_t arg2 asm("r4") = (uint64_t)retaddr;
+ register uint64_t arg3 asm("r5") = (uint64_t)fdt;
+
+ asm volatile("sc 2\n"
+ : "=r"(arg1)
+ : "r"(func), "0"(arg1), "r"(arg2), "r"(arg3)
+ :);
+
+ return (int)arg1;
+}
+
+/*
+ * Call the Ultravisor to transfer us to secure memory if we have an ESM blob.
+ */
+static void setup_secure_guest(void *fdt)
+{
+ void *esm_blob;
+ int ret;
+
+ if (prom_svm_disable) {
+ prom_printf("Secure mode is OFF\n");
+ return;
+ }
+
+ esm_blob = get_esm_blob();
+ if (esm_blob == NULL)
+ /*
+ * Absence of an ESM blob isn't an error, it just means we
+ * shouldn't switch to secure mode.
+ */
+ return;
+
+ /* Switch to secure mode. */
+ prom_printf("Switching to secure mode.\n");
+
+ ret = enter_secure_mode(esm_blob, NULL, fdt);
+ if (ret != U_SUCCESS) {
+ prom_printf("Returned %d from switching to secure mode.\n", ret);
+ prom_rtas_os_term("Switch to secure mode failed.\n");
+ }
+}
+#else
+static void setup_secure_guest(void *fdt)
+{
+}
+#endif /* CONFIG_PPC_SVM */
+
/*
* We enter here early on, when the Open Firmware prom is still
* handling exceptions and the MMU hash table for us.
@@ -3360,6 +3481,9 @@ unsigned long __init prom_init(unsigned long r3, unsigned long r4,
unreloc_toc();
#endif

+ /* Move to secure memory if we're supposed to be secure guests. */
+ setup_secure_guest((void *)hdr);
+
__start(hdr, kbase, 0, 0, 0, 0, 0);

return 0;