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FROMGIT: KVM: arm64: Flush hyp bss section after initialization of variables in bss

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To determine CPU features during initialization, the nVHE hypervisor
utilizes sanitized values of the host's CPU features registers. These
values, stored in u64 idaa64*_el1_sys_val variables are updated by the
kvm_hyp_init_symbols() function at EL1. To ensure EL2 visibility with
the MMU off, the data cache needs to be flushed after these updates.
However, individually flushing each variable using
kvm_flush_dcache_to_poc() is inefficient.

These cpu feature variables would be part of the bss section of
the hypervisor. Hence, flush the entire bss section of hypervisor
once the initialization is complete.

Fixes: 6c30bfb18d ("KVM: arm64: Add handlers for protected VM System Registers")

Bug: b/386889513
Bug: 357781595
Change-Id: Ib988dbc23ea401e0af1cd6e5445151af868c844c
Link: https://lore.kernel.org/all/20250121044016.2219256-1-lokeshvutla@google.com/
(cherry picked from commit 9bcbb6104a344d3526e185ee1e7b985509914e90
 https://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git/ fixes)
Suggested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@google.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
This commit is contained in:
Lokesh Vutla
2025-01-20 10:29:34 +00:00
committed by Fuad Tabba
parent 2f2e115eec
commit 11620ab958
1 changed files with 6 additions and 0 deletions
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6
arch/arm64/kvm/arm.c
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@@ -2084,6 +2084,12 @@ static void kvm_hyp_init_symbols(void)
kvm_nvhe_sym(kvm_arm_vmid_bits) = kvm_arm_vmid_bits;
kvm_nvhe_sym(smccc_trng_available) = smccc_trng_available;
kvm_nvhe_sym(kvm_host_sve_max_vl) = kvm_host_sve_max_vl;
/*
* Flush entire BSS since part of its data is read while the MMU is off.
*/
kvm_flush_dcache_to_poc(kvm_ksym_ref(__hyp_bss_start),
kvm_ksym_ref(__hyp_bss_end) - kvm_ksym_ref(__hyp_bss_start));
}
int kvm_hyp_init_events(void);