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make IPI barrier a real function
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Axel Heider authored and Axel Heider committed Jun 20, 2024
1 parent 0931cf0 commit 83755b3
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Showing 8 changed files with 37 additions and 23 deletions.
11 changes: 11 additions & 0 deletions include/arch/arm/arch/machine.h
Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,17 @@ static inline void arch_pause(void)
{
/* TODO */
}

static inline void ipi_mem_barrier(void)
{
/* For GICv2 systems a dmb() is sufficient, but it's not enough with GICv3
* due to the way IPIs is triggered (memory-mapped or MSR inst.). A dmb()
* does not prevent re-ordering to happen between memory accesses and
* instructions, this guarantee requires a dsb().
*/
dsb_ishst();
}

#endif /* ENABLE_SMP_SUPPORT */

/* Update the value of the actual regsiter to hold the expected value */
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10 changes: 0 additions & 10 deletions include/arch/arm/arch/machine/hardware.h
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Expand Up @@ -19,17 +19,7 @@ typedef word_t vm_fault_type_t;
#define PAGE_BASE(_p, _s) ((_p) & ~MASK(pageBitsForSize((_s))))
#define PAGE_OFFSET(_p, _s) ((_p) & MASK(pageBitsForSize((_s))))

#define IPI_MEM_BARRIER \
do { \
/* This can be relaxed for GICv2 but for GICv3 dmb() no longer works */ \
/* since the way IPI is triggered is different (memory-mapped or MSR inst.) */ \
/* and dmb() is not able to avoid re-ordering between memory accesses and */ \
/* instructions. In order to support both GICv2 and v3 dsb() is required. */ \
dsb_ishst(); \
} while (0)

#endif /* __ASSEMBLER__ */

#define L1_CACHE_LINE_SIZE_BITS CONFIG_L1_CACHE_LINE_SIZE_BITS
#define L1_CACHE_LINE_SIZE BIT(L1_CACHE_LINE_SIZE_BITS)

4 changes: 4 additions & 0 deletions include/arch/riscv/arch/machine.h
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Expand Up @@ -71,6 +71,10 @@ static inline void fence_rw_rw(void)
asm volatile("fence rw, rw" ::: "memory");
}

static inline void ipi_mem_barrier(void) {
fence_rw_rw();
}

static inline void fence_w_rw(void)
{
asm volatile("fence w, rw" ::: "memory");
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6 changes: 0 additions & 6 deletions include/arch/riscv/arch/machine/hardware.h
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Expand Up @@ -122,9 +122,3 @@ static inline void arch_clean_invalidate_caches(void)

#define LOAD_S STRINGIFY(LOAD)
#define STORE_S STRINGIFY(STORE)

#define IPI_MEM_BARRIER \
do { \
asm volatile("fence rw,rw" ::: "memory"); \
} while (0)

12 changes: 10 additions & 2 deletions include/arch/x86/arch/kernel/x2apic.h
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Expand Up @@ -65,6 +65,14 @@ static inline void apic_write_icr(word_t high, word_t low)
x86_wrmsr(APIC_ICR, icr);
}

#define IPI_ICR_BARRIER asm volatile("mfence" ::: "memory")
#define IPI_MEM_BARRIER IPI_ICR_BARRIER
static inline void ipi_icr_barrier(void)
{
asm volatile("mfence" ::: "memory");
}

static inline void ipi_mem_barrier(void)
{
IPI_ICR_BARRIER;
}

#endif /* CONFIG_X2APIC */
13 changes: 10 additions & 3 deletions include/arch/x86/arch/kernel/xapic.h
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Expand Up @@ -66,7 +66,14 @@ static inline void apic_write_icr(word_t high, word_t low)
apic_write_reg(APIC_ICR1, low);
}

#define IPI_ICR_BARRIER asm volatile("" ::: "memory")
#define IPI_MEM_BARRIER IPI_ICR_BARRIER
#endif /* CONFIG_XAPIC */
static inline void ipi_icr_barrier(void)
{
asm volatile("" ::: "memory");
}

static inline void ipi_mem_barrier(void)
{
ipi_icr_barrier();
}

#endif /* CONFIG_XAPIC */
2 changes: 1 addition & 1 deletion src/arch/x86/smp/ipi.c
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Expand Up @@ -110,7 +110,7 @@ static void x86_ipi_send_mask(interrupt_t ipi, word_t mask, bool_t isBlocking)
} while (mask != 0);

/* broadcast IPIs to clusters... */
IPI_ICR_BARRIER;
ipi_icr_barrier();
for (int i = 0; i < nr_target_clusters; i++) {
apic_send_ipi_cluster(ipi, target_clusters[i]);
}
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2 changes: 1 addition & 1 deletion src/smp/ipi.c
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Expand Up @@ -139,7 +139,7 @@ void generic_ipi_send_mask(irq_t ipi, word_t mask, bool_t isBlocking)

if (nr_target_cores > 0) {
/* sending IPIs... */
IPI_MEM_BARRIER;
ipi_mem_barrier();
for (int i = 0; i < nr_target_cores; i++) {
ipi_send_target(ipi, cpuIndexToID(target_cores[i]));
}
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