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fix(cm): make ICC_SRE_EL2 fixup generic to all worlds

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For ICC_SRE_EL2.SRE the Arm ARM specifies that "If software changes this
bit from 1 to 0, the results are UNPREDICTABLE". However, the
indiscriminate zeroing of the EL2 context does just that for Secure and
Realm worlds. Make this fixup generic to avoid the problem.

Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Change-Id: Iee21ace17faf10eae52a046e6dfafc5141fa7f85
This commit is contained in:
Boyan Karatotev 2023-05-23 12:04:00 +01:00 • committed by Jayanth Dodderi Chidanand
parent f0c96a2e35
commit 5e8cc72786
1 changed files with 18 additions and 9 deletions
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27
lib/el3_runtime/aarch64/context_mgmt.c
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@ -270,15 +270,6 @@ static void setup_ns_context(cpu_context_t *ctx, const struct entry_point_info *
write_ctx_reg(get_el2_sysregs_ctx(ctx), CTX_SCTLR_EL2,
sctlr_el2);
/*
* Program the ICC_SRE_EL2 to make sure the correct bits are set
* when restoring NS context.
*/
u_register_t icc_sre_el2 = ICC_SRE_DIB_BIT | ICC_SRE_DFB_BIT |
ICC_SRE_EN_BIT | ICC_SRE_SRE_BIT;
write_ctx_reg(get_el2_sysregs_ctx(ctx), CTX_ICC_SRE_EL2,
icc_sre_el2);
if (is_feat_hcx_supported()) {
/*
* Initialize register HCRX_EL2 with its init value.
@ -330,6 +321,24 @@ static void setup_context_common(cpu_context_t *ctx, const entry_point_info_t *e
/* Clear any residual register values from the context */
zeromem(ctx, sizeof(*ctx));
/*
* The lower-EL context is zeroed so that no stale values leak to a world.
* It is assumed that an all-zero lower-EL context is good enough for it
* to boot correctly. However, there are very few registers where this
* is not true and some values need to be recreated.
*/
#if CTX_INCLUDE_EL2_REGS
el2_sysregs_t *el2_ctx = get_el2_sysregs_ctx(ctx);
/*
* These bits are set in the gicv3 driver. Losing them (especially the
* SRE bit) is problematic for all worlds. Henceforth recreate them.
*/
u_register_t icc_sre_el2 = ICC_SRE_DIB_BIT | ICC_SRE_DFB_BIT |
ICC_SRE_EN_BIT | ICC_SRE_SRE_BIT;
write_ctx_reg(el2_ctx, CTX_ICC_SRE_EL2, icc_sre_el2);
#endif /* CTX_INCLUDE_EL2_REGS */
/*
* SCR_EL3 was initialised during reset sequence in macro
* el3_arch_init_common. This code modifies the SCR_EL3 fields that