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lib: sbi: Synchronize PMP settings with virtual memory system

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As per section 3.7.2 of RISC-V Privileged Specification,
PMP settings must be synchronized with the virtual memory
system after PMP settings have been written.

Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Himanshu Chauhan 2022-12-05 22:12:31 +05:30 • committed by Anup Patel
parent 7b087781c2
commit cb568b9b29
1 changed files with 22 additions and 0 deletions
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22
lib/sbi/sbi_hart.c
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@ -22,6 +22,7 @@
#include <sbi/sbi_pmu.h>
#include <sbi/sbi_string.h>
#include <sbi/sbi_trap.h>
#include <sbi/sbi_hfence.h>
extern void __sbi_expected_trap(void);
extern void __sbi_expected_trap_hext(void);
@ -321,6 +322,27 @@ int sbi_hart_pmp_configure(struct sbi_scratch *scratch)
}
}
/*
* As per section 3.7.2 of privileged specification v1.12,
* virtual address translations can be speculatively performed
* (even before actual access). These, along with PMP traslations,
* can be cached. This can pose a problem with CPU hotplug
* and non-retentive suspend scenario because PMP states are
* not preserved.
* It is advisable to flush the caching structures under such
* conditions.
*/
if (misa_extension('S')) {
__asm__ __volatile__("sfence.vma");
/*
* If hypervisor mode is supported, flush caching
* structures in guest mode too.
*/
if (misa_extension('H'))
__sbi_hfence_gvma_all();
}
return 0;
}