Commit 1d81d15d authored by James Morse's avatar James Morse Committed by Borislav Petkov
Browse files

x86/resctrl: Move mbm_overflow_count() into resctrl_arch_rmid_read() 



resctrl_arch_rmid_read() is intended as the function that an
architecture agnostic resctrl filesystem driver can use to
read a value in bytes from a counter. Currently the function returns
the MBM values in chunks directly from hardware. When reading a bandwidth
counter, mbm_overflow_count() must be used to correct for any possible
overflow.

mbm_overflow_count() is architecture specific, its behaviour should
be part of resctrl_arch_rmid_read().

Move the mbm_overflow_count() calls into resctrl_arch_rmid_read().
This allows the resctrl filesystems's prev_msr to be removed in
favour of the architecture private version.

Signed-off-by: default avatarJames Morse <james.morse@arm.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarJamie Iles <quic_jiles@quicinc.com>
Reviewed-by: default avatarShaopeng Tan <tan.shaopeng@fujitsu.com>
Reviewed-by: default avatarReinette Chatre <reinette.chatre@intel.com>
Tested-by: default avatarXin Hao <xhao@linux.alibaba.com>
Tested-by: default avatarShaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: default avatarCristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20220902154829.30399-18-james.morse@arm.com
parent 8286618a

arch/x86/kernel/cpu/resctrl/internal.h

+0 −2
Original line number Diff line number Diff line
@@ -281,7 +281,6 @@ struct rftype { 
/**

 * struct mbm_state - status for each MBM counter in each domain

 * @chunks:	Total data moved (multiply by rdt_group.mon_scale to get bytes)

 * @prev_msr:	Value of IA32_QM_CTR for this RMID last time we read it

 * @prev_bw_chunks: Previous chunks value read for bandwidth calculation

 * @prev_bw:	The most recent bandwidth in MBps

 * @delta_bw:	Difference between the current and previous bandwidth
@@ -289,7 +288,6 @@ struct rftype { 
 */

struct mbm_state {

	u64	chunks;

	u64	prev_msr;

	u64	prev_bw_chunks;

	u32	prev_bw;

	u32	delta_bw;

arch/x86/kernel/cpu/resctrl/monitor.c

+20 −15
Original line number Diff line number Diff line
@@ -167,9 +167,20 @@ void resctrl_arch_reset_rmid(struct rdt_resource *r, struct rdt_domain *d, 
		memset(am, 0, sizeof(*am));

}



static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr, unsigned int width)

{

	u64 shift = 64 - width, chunks;



	chunks = (cur_msr << shift) - (prev_msr << shift);

	return chunks >> shift;

}



int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain *d,

			   u32 rmid, enum resctrl_event_id eventid, u64 *val)

{

	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);

	struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(d);

	struct arch_mbm_state *am;

	u64 msr_val;



	if (!cpumask_test_cpu(smp_processor_id(), &d->cpu_mask))
@@ -191,7 +202,13 @@ int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain *d, 
	if (msr_val & RMID_VAL_UNAVAIL)

		return -EINVAL;



	am = get_arch_mbm_state(hw_dom, rmid, eventid);

	if (am) {

		*val = mbm_overflow_count(am->prev_msr, msr_val, hw_res->mbm_width);

		am->prev_msr = msr_val;

	} else {

		*val = msr_val;

	}



	return 0;

}
@@ -322,19 +339,10 @@ void free_rmid(u32 rmid) 
		list_add_tail(&entry->list, &rmid_free_lru);

}



static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr, unsigned int width)

{

	u64 shift = 64 - width, chunks;



	chunks = (cur_msr << shift) - (prev_msr << shift);

	return chunks >> shift;

}



static int __mon_event_count(u32 rmid, struct rmid_read *rr)

{

	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(rr->r);

	struct mbm_state *m;

	u64 chunks, tval = 0;

	u64 tval = 0;



	if (rr->first)

		resctrl_arch_reset_rmid(rr->r, rr->d, rmid, rr->evtid);
@@ -363,13 +371,10 @@ static int __mon_event_count(u32 rmid, struct rmid_read *rr) 


	if (rr->first) {

		memset(m, 0, sizeof(struct mbm_state));

		m->prev_msr = tval;

		return 0;

	}



	chunks = mbm_overflow_count(m->prev_msr, tval, hw_res->mbm_width);

	m->chunks += chunks;

	m->prev_msr = tval;

	m->chunks += tval;



	rr->val += get_corrected_mbm_count(rmid, m->chunks);