Enable ARMv8.6-FGT when booting to EL2

The Fine Grained Traps (FGT) architecture extension was added to aarch64 in
ARMv8.6. This extension primarily allows hypervisors, at EL2, to trap specific
instructions in a more fine grained manner, with an enable bit for each
instruction. This patch adds support for this extension by enabling the
extension when booting an hypervisor at EL2.

Change-Id: Idb9013ed118b6a1b7b76287237096de992ca4da3
Signed-off-by: Jimmy Brisson <jimmy.brisson@arm.com>

include/arch/aarch64/arch.h

@@ -211,6 +211,11 @@
 #define PARANGE_0101	U(48)
 #define PARANGE_0110	U(52)
 
+#define ID_AA64MMFR0_EL1_FGT_SHIFT		U(56)
+#define ID_AA64MMFR0_EL1_FGT_MASK		ULL(0xf)
+#define ID_AA64MMFR0_EL1_FGT_SUPPORTED		ULL(0x1)
+#define ID_AA64MMFR0_EL1_FGT_NOT_SUPPORTED	ULL(0x0)
+
 #define ID_AA64MMFR0_EL1_TGRAN4_SHIFT		U(28)
 #define ID_AA64MMFR0_EL1_TGRAN4_MASK		ULL(0xf)
 #define ID_AA64MMFR0_EL1_TGRAN4_SUPPORTED	ULL(0x0)
@@ -324,6 +329,7 @@
 #define SCR_TWEDEL_SHIFT	U(30)
 #define SCR_TWEDEL_MASK		ULL(0xf)
 #define SCR_TWEDEn_BIT		(UL(1) << 29)
+#define SCR_FGTEN_BIT           (U(1) << 27)
 #define SCR_ATA_BIT		(U(1) << 26)
 #define SCR_FIEN_BIT		(U(1) << 21)
 #define SCR_EEL2_BIT		(U(1) << 18)

include/arch/aarch64/arch_features.h

@@ -64,6 +64,12 @@ static inline bool is_armv8_6_twed_present(void)
 		ID_AA64MMFR1_EL1_TWED_MASK) == ID_AA64MMFR1_EL1_TWED_SUPPORTED);
 }
 
+static inline bool is_armv8_6_fgt_present(void)
+{
+	return ((read_id_aa64mmfr0_el1() >> ID_AA64MMFR0_EL1_FGT_SHIFT) &
+		ID_AA64MMFR0_EL1_FGT_MASK) == ID_AA64MMFR0_EL1_FGT_SUPPORTED;
+}
+
 /*
  * Return MPAM version:
  *

lib/el3_runtime/aarch64/context_mgmt.c

@@ -173,11 +173,18 @@ void cm_setup_context(cpu_context_t *ctx, const entry_point_info_t *ep)
 	 * SCR_EL3.HCE: Enable HVC instructions if next execution state is
 	 * AArch64 and next EL is EL2, or if next execution state is AArch32 and
 	 * next mode is Hyp.
+	 * SCR_EL3.FGTEn: Enable Fine Grained Virtualization Traps under the
+	 * same conditions as HVC instructions and when the processor supports
+	 * ARMv8.6-FGT.
 	 */
 	if (((GET_RW(ep->spsr) == MODE_RW_64) && (GET_EL(ep->spsr) == MODE_EL2))
 	    || ((GET_RW(ep->spsr) != MODE_RW_64)
 		&& (GET_M32(ep->spsr) == MODE32_hyp))) {
 		scr_el3 |= SCR_HCE_BIT;
+
+		if (is_armv8_6_fgt_present()) {
+			scr_el3 |= SCR_FGTEN_BIT;
+		}
 	}
 
 	/* Enable S-EL2 if the next EL is EL2 and security state is secure */