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

Alexey Kardashevskiy
2019-06-26T07:44:45Z

On 21/05/2019 14:49, Thiago Jung Bauermann wrote:
> 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)

This is just an rtas hcall, nothing special about "os-term".

> +{
> + 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;
>

--
Alexey