[boot-wrapper,v4,2/4] aarch64: Enable Armv8-R EL2 boot

Commit Message

Luca Fancellu Oct. 17, 2024, 9:55 a.m. UTC

When booting on Armv8-R, EL3 is not implemented and the Linux
kernel needs to be booted in EL1, so initialise EL2 and start
the kernel in the expected exception level.

To do so, introduce the 'aarch64-r' argument for the
--with-bw-arch parameter.

PSCI is not yet implemented for aarch64-r.

Signed-off-by: Luca Fancellu <[e-mail]>
---
v4 changes:
 - Remove _NOTRAP from HCR_EL2_*_NOTRAP registers
 - split checks for Armv8-R inside ID_AA64MMFR0_EL1
 - reworked cpu_init_arch code to don't have #ifdef
---
 Makefile.am                    |  4 ++
 arch/aarch64/boot.S            |  5 +++
 arch/aarch64/include/asm/cpu.h | 24 ++++++++++++
 arch/aarch64/init.c            | 68 +++++++++++++++++++++++++++++++++-
 configure.ac                   |  8 ++--
 5 files changed, 105 insertions(+), 4 deletions(-)

Patch

diff --git a/Makefile.am b/Makefile.am
index 6ee6afac9535..44ea3f7e0d7b 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -39,6 +39,10 @@  DEFINES		+= $(if $(SYSREGS_BASE), -DSYSREGS_BASE=$(SYSREGS_BASE), )
 DEFINES		+= -DUART_BASE=$(UART_BASE)
 DEFINES		+= -DSTACK_SIZE=256
 
+if BOOTWRAPPER_64R
+DEFINES		+= -DBOOTWRAPPER_64R
+endif
+
 if KERNEL_32
 DEFINES		+= -DKERNEL_32
 PSCI_CPU_ON	:= 0x84000003
diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S
index 5060a6d5258f..565397823cb4 100644
--- a/arch/aarch64/boot.S
+++ b/arch/aarch64/boot.S
@@ -100,7 +100,12 @@  ASM_FUNC(jump_kernel)
 	mov	x1, x21
 	mov	x2, x22
 	mov	x3, x23
+#if defined(BOOTWRAPPER_64R)
+	// On Armv8-R Linux needs to be booted at EL1
+	mov	x4, #SPSR_KERNEL_EL1
+#else
 	mov	x4, #SPSR_KERNEL
+#endif
 
 	/*
 	 * If bit 0 of the kernel address is set, we're entering in AArch32
diff --git a/arch/aarch64/include/asm/cpu.h b/arch/aarch64/include/asm/cpu.h
index a5744e16e4b2..0a6baa84bd72 100644
--- a/arch/aarch64/include/asm/cpu.h
+++ b/arch/aarch64/include/asm/cpu.h
@@ -32,10 +32,15 @@ 
 	(BIT(29) | BIT(28) | BIT(23) | BIT(22) | BIT(18) | BIT(16) |	\
 	 BIT(11) | BIT(5) | BIT(4))
 
+#define CPTR_EL2_NO_E2H_RES1					\
+	(BITS(13,12) | BIT(9) | BITS(7,0))
+
 #define SCTLR_EL2_RES1							\
 	(BIT(29) | BIT(28) | BIT(23) | BIT(22) | BIT(18) | BIT(16) |	\
 	 BIT(11) | BIT(5) | BIT(4))
 
+#define VSTCR_EL2_RES1							(BIT(31))
+
 #define SCTLR_EL1_RES1							\
 	(BIT(29) | BIT(28) | BIT(23) | BIT(22) | BIT(20) | BIT(11) |	\
 	 BIT(8) | BIT(7) | BIT(4))
@@ -64,7 +69,13 @@ 
 #define SCR_EL3_PIEN			BIT(45)
 #define SCR_EL3_D128En			BIT(47)
 
+#define VTCR_EL2_MSA			BIT(31)
+
 #define HCR_EL2_RES1			BIT(1)
+#define HCR_EL2_APK			BIT(40)
+#define HCR_EL2_API			BIT(41)
+#define HCR_EL2_FIEN			BIT(47)
+#define HCR_EL2_EnSCXT			BIT(53)
 
 #define ID_AA64DFR0_EL1_PMSVER		BITS(35, 32)
 #define ID_AA64DFR0_EL1_TRACEBUFFER	BITS(47, 44)
@@ -81,6 +92,8 @@ 
 #define ID_AA64ISAR2_EL1_GPA3		BITS(11, 8)
 #define ID_AA64ISAR2_EL1_APA3		BITS(15, 12)
 
+#define ID_AA64MMFR0_EL1_MSA		BITS(51, 48)
+#define ID_AA64MMFR0_EL1_MSA_frac	BITS(55, 52)
 #define ID_AA64MMFR0_EL1_FGT		BITS(59, 56)
 #define ID_AA64MMFR0_EL1_ECV		BITS(63, 60)
 
@@ -96,8 +109,12 @@ 
 
 #define ID_AA64PFR1_EL1_MTE		BITS(11, 8)
 #define ID_AA64PFR1_EL1_SME		BITS(27, 24)
+#define ID_AA64PFR1_EL1_CSV2_frac	BITS(35, 32)
 #define ID_AA64PFR1_EL1_THE		BITS(51, 48)
+
+#define ID_AA64PFR0_EL1_RAS		BITS(31, 28)
 #define ID_AA64PFR0_EL1_SVE		BITS(35, 32)
+#define ID_AA64PFR0_EL1_CSV2		BITS(59, 56)
 
 #define ID_AA64SMFR0_EL1		s3_0_c0_c4_5
 #define ID_AA64SMFR0_EL1_FA64		BIT(63)
@@ -106,7 +123,9 @@ 
  * Initial register values required for the boot-wrapper to run out-of-reset.
  */
 #define SCTLR_EL3_RESET		SCTLR_EL3_RES1
+#define CPTR_EL2_RESET		CPTR_EL2_NO_E2H_RES1
 #define SCTLR_EL2_RESET		SCTLR_EL2_RES1
+#define VSTCR_EL2_RESET		VSTCR_EL2_RES1
 #define SCTLR_EL1_RESET		SCTLR_EL1_RES1
 #define HCR_EL2_RESET		HCR_EL2_RES1
 
@@ -123,6 +142,7 @@ 
 #define SPSR_I			(1 << 7)	/* IRQ masked */
 #define SPSR_F			(1 << 6)	/* FIQ masked */
 #define SPSR_T			(1 << 5)	/* Thumb */
+#define SPSR_EL1H		(5 << 0)	/* EL1 Handler mode */
 #define SPSR_EL2H		(9 << 0)	/* EL2 Handler mode */
 #define SPSR_HYP		(0x1a << 0)	/* M[3:0] = hyp, M[4] = AArch32 */
 
@@ -135,6 +155,9 @@ 
 #define ICC_CTLR_EL3		S3_6_C12_C12_4
 #define ICC_PMR_EL1		S3_0_C4_C6_0
 
+#define VSTCR_EL2		s3_4_c2_c6_2
+#define VSCTLR_EL2		s3_4_c2_c0_0
+
 #define ZCR_EL3			s3_6_c1_c2_0
 #define ZCR_EL3_LEN_MAX		0xf
 
@@ -162,6 +185,7 @@ 
 #else
 #define SCTLR_EL1_KERNEL	SCTLR_EL1_RES1
 #define SPSR_KERNEL		(SPSR_A | SPSR_D | SPSR_I | SPSR_F | SPSR_EL2H)
+#define SPSR_KERNEL_EL1		(SPSR_A | SPSR_D | SPSR_I | SPSR_F | SPSR_EL1H)
 #endif
 
 #ifndef __ASSEMBLY__
diff --git a/arch/aarch64/init.c b/arch/aarch64/init.c
index 63fa949653ee..9bbfce3aaf34 100644
--- a/arch/aarch64/init.c
+++ b/arch/aarch64/init.c
@@ -54,6 +54,27 @@  static inline bool cpu_has_permission_indirection(void)
 	return mrs(ID_AA64MMFR3_EL1) & mask;
 }
 
+static bool cpu_has_scxt(void)
+{
+	unsigned long csv2 = mrs_field(ID_AA64PFR0_EL1, CSV2);
+
+	if (csv2 >= 2)
+		return true;
+	if (csv2 < 1)
+		return false;
+
+	return mrs_field(ID_AA64PFR1_EL1, CSV2_frac) >= 2;
+}
+
+static inline bool bootwrapper_is_r_class(void)
+{
+#ifdef BOOTWRAPPER_64R
+	return true;
+#else
+	return false;
+#endif
+}
+
 static void cpu_init_el3(void)
 {
 	unsigned long scr = SCR_EL3_RES1 | SCR_EL3_NS | SCR_EL3_HCE;
@@ -157,6 +178,47 @@  static void cpu_init_el3(void)
 	}
 }
 
+void cpu_init_el2_armv8r(void)
+{
+	unsigned long hcr = mrs(hcr_el2);
+
+	/* On Armv8-R ID_AA64MMFR0_EL1[51:48] == 0xF */
+	if (mrs_field(ID_AA64MMFR0_EL1, MSA) != 0xF) {
+		print_string("ID_AA64MMFR0_EL1.MSA != 0xF, not R-class\r\n");
+		while (1)
+			wfe();
+	}
+
+	if (mrs_field(ID_AA64MMFR0_EL1, MSA_frac) < 2) {
+		print_string("ID_AA64MMFR0_EL1.MSA_frac < 2, EL1&0 VMSA not supported\r\n");
+		while (1)
+			wfe();
+	}
+
+	msr(vpidr_el2, mrs(midr_el1));
+	msr(vmpidr_el2, mrs(mpidr_el1));
+
+	msr(VSCTLR_EL2, 0);
+	msr(VSTCR_EL2, VSTCR_EL2_RESET);
+	msr(vtcr_el2, VTCR_EL2_MSA);
+
+	msr(cntvoff_el2, 0);
+	msr(cptr_el2, CPTR_EL2_RESET);
+	msr(mdcr_el2, 0);
+
+	if (cpu_has_scxt())
+		hcr |= HCR_EL2_EnSCXT;
+
+	if (mrs_field(ID_AA64PFR0_EL1, RAS) >= 2)
+		hcr |= HCR_EL2_FIEN;
+
+	if (cpu_has_pauth())
+		hcr |= HCR_EL2_APK | HCR_EL2_API;
+
+	msr(hcr_el2, hcr);
+	isb();
+}
+
 #ifdef PSCI
 extern char psci_vectors[];
 
@@ -176,11 +238,15 @@  static void cpu_init_psci_arch(unsigned int cpu) { }
 
 void cpu_init_arch(unsigned int cpu)
 {
-	if (mrs(CurrentEL) == CURRENTEL_EL3) {
+	if (!bootwrapper_is_r_class() && mrs(CurrentEL) == CURRENTEL_EL3) {
 		cpu_init_el3();
 		gic_secure_init();
 	}
 
+	if (bootwrapper_is_r_class() && mrs(CurrentEL) == CURRENTEL_EL2) {
+		cpu_init_el2_armv8r();
+	}
+
 	cpu_init_psci_arch(cpu);
 
 	msr(CNTFRQ_EL0, COUNTER_FREQ);
diff --git a/configure.ac b/configure.ac
index a1d2846a6865..95e2b7f05756 100644
--- a/configure.ac
+++ b/configure.ac
@@ -9,14 +9,16 @@  AC_INIT([boot-wrapper], [v0.2])
 
 AM_INIT_AUTOMAKE([foreign])
 
-# Allow a user to pass --with-bw-arch={aarch64-a,aarch32-a}
+# Allow a user to pass --with-bw-arch={aarch64-a,aarch32-a,aarch64-r}
 AC_ARG_WITH([bw-arch],
-	AS_HELP_STRING([--with-bw-arch], [specify boot-wrapper architecture: aarch64-a (default) or aarch32-a]),
+	AS_HELP_STRING([--with-bw-arch], [specify boot-wrapper architecture: aarch64-a (default), aarch32-a or aarch64-r]),
 	[case "${withval}" in
 		no|yes|aarch64-a) USE_ARCH=aarch64-a ;;
 		aarch32-a) USE_ARCH=aarch32-a ;;
-		*) AC_MSG_ERROR([Bad value "${withval}" for --with-bw-arch. Use "aarch64-a" or "aarch32-a"]) ;;
+		aarch64-r) USE_ARCH=aarch64-r ;;
+		*) AC_MSG_ERROR([Bad value "${withval}" for --with-bw-arch. Use "aarch64-a", "aarch32-a" or "aarch64-r"]) ;;
 	esac])
+AM_CONDITIONAL([BOOTWRAPPER_64R], [test "x$USE_ARCH" = "xaarch64-r"])
 
 AS_IF([test "x$USE_ARCH" = "xaarch32-a"],
 	[BOOTWRAPPER_ES=32], [BOOTWRAPPER_ES=64]