Subject: Re: [PATCH v6 3/6] KVM: PPC: Book3S HV: Add support for H_RPT_INVALIDATE

From: Bharata B Rao <[email-masked]>
Date: Tue, 23 Mar 2021 09:35:32 +0530

On Tue, Mar 23, 2021 at 01:26:56PM +1100, David Gibson wrote:
> On Thu, Mar 11, 2021 at 02:09:36PM +0530, Bharata B Rao wrote:
> > H_RPT_INVALIDATE does two types of TLB invalidations:
> > 
> > 1. Process-scoped invalidations for guests when LPCR[GTSE]=0.
> >    This is currently not used in KVM as GTSE is not usually
> >    disabled in KVM.
> > 2. Partition-scoped invalidations that an L1 hypervisor does on
> >    behalf of an L2 guest. This is currently handled
> >    by H_TLB_INVALIDATE hcall and this new replaces the old that.
> > 
> > This commit enables process-scoped invalidations for L1 guests.
> > Support for process-scoped and partition-scoped invalidations
> > from/for nested guests will be added separately.
> > 
> > Process scoped tlbie invalidations from L1 and nested guests
> > need RS register for TLBIE instruction to contain both PID and
> > LPID.  This patch introduces primitives that execute tlbie
> > instruction with both PID and LPID set in prepartion for
> > H_RPT_INVALIDATE hcall.
> > 
> > A description of H_RPT_INVALIDATE follows:
> > 
> > int64   /* H_Success: Return code on successful completion */
> >         /* H_Busy - repeat the call with the same */
> >         /* H_Parameter, H_P2, H_P3, H_P4, H_P5 : Invalid
> > 	   parameters */
> > hcall(const uint64 H_RPT_INVALIDATE, /* Invalidate RPT
> > 					translation
> > 					lookaside information */
> >       uint64 id,        /* PID/LPID to invalidate */
> >       uint64 target,    /* Invalidation target */
> >       uint64 type,      /* Type of lookaside information */
> >       uint64 pg_sizes,  /* Page sizes */
> >       uint64 start,     /* Start of Effective Address (EA)
> > 			   range (inclusive) */
> >       uint64 end)       /* End of EA range (exclusive) */
> > 
> > Invalidation targets (target)
> > -----------------------------
> > Core MMU        0x01 /* All virtual processors in the
> > 			partition */
> > Core local MMU  0x02 /* Current virtual processor */
> > Nest MMU        0x04 /* All nest/accelerator agents
> > 			in use by the partition */
> > 
> > A combination of the above can be specified,
> > except core and core local.
> > 
> > Type of translation to invalidate (type)
> > ---------------------------------------
> > NESTED       0x0001  /* invalidate nested guest partition-scope */
> > TLB          0x0002  /* Invalidate TLB */
> > PWC          0x0004  /* Invalidate Page Walk Cache */
> > PRT          0x0008  /* Invalidate caching of Process Table
> > 			Entries if NESTED is clear */
> > PAT          0x0008  /* Invalidate caching of Partition Table
> > 			Entries if NESTED is set */
> > 
> > A combination of the above can be specified.
> > 
> > Page size mask (pages)
> > ----------------------
> > 4K              0x01
> > 64K             0x02
> > 2M              0x04
> > 1G              0x08
> > All sizes       (-1UL)
> > 
> > A combination of the above can be specified.
> > All page sizes can be selected with -1.
> > 
> > Semantics: Invalidate radix tree lookaside information
> >            matching the parameters given.
> > * Return H_P2, H_P3 or H_P4 if target, type, or pageSizes parameters
> >   are different from the defined values.
> > * Return H_PARAMETER if NESTED is set and pid is not a valid nested
> >   LPID allocated to this partition
> > * Return H_P5 if (start, end) doesn't form a valid range. Start and
> >   end should be a valid Quadrant address and  end > start.
> > * Return H_NotSupported if the partition is not in running in radix
> >   translation mode.
> > * May invalidate more translation information than requested.
> > * If start = 0 and end = -1, set the range to cover all valid
> >   addresses. Else start and end should be aligned to 4kB (lower 11
> >   bits clear).
> > * If NESTED is clear, then invalidate process scoped lookaside
> >   information. Else pid specifies a nested LPID, and the invalidation
> >   is performed   on nested guest partition table and nested guest
> >   partition scope real addresses.
> > * If pid = 0 and NESTED is clear, then valid addresses are quadrant 3
> >   and quadrant 0 spaces, Else valid addresses are quadrant 0.
> > * Pages which are fully covered by the range are to be invalidated.
> >   Those which are partially covered are considered outside
> >   invalidation range, which allows a caller to optimally invalidate
> >   ranges that may   contain mixed page sizes.
> > * Return H_SUCCESS on success.
> > 
> > Signed-off-by: Bharata B Rao <[email-masked]>
> 
> Reviewed-by: David Gibson <[email-masked]>
> 
> with the exception of one nit noted below.
> 
> > ---
> >  .../include/asm/book3s/64/tlbflush-radix.h    |   4 +
> >  arch/powerpc/include/asm/mmu_context.h        |  11 ++
> >  arch/powerpc/kvm/book3s_hv.c                  |  46 ++++++
> >  arch/powerpc/mm/book3s64/radix_tlb.c          | 152 +++++++++++++++++-
> >  4 files changed, 209 insertions(+), 4 deletions(-)
> > 
> > diff --git a/arch/powerpc/include/asm/book3s/64/tlbflush-radix.h b/arch/powerpc/include/asm/book3s/64/tlbflush-radix.h
> > index 8b33601cdb9d..a46fd37ad552 100644
> > --- a/arch/powerpc/include/asm/book3s/64/tlbflush-radix.h
> > +++ b/arch/powerpc/include/asm/book3s/64/tlbflush-radix.h
> > @@ -4,6 +4,10 @@
> >  
> >  #include <asm/hvcall.h>
> >  
> > +#define RIC_FLUSH_TLB 0
> > +#define RIC_FLUSH_PWC 1
> > +#define RIC_FLUSH_ALL 2
> 
> Is there a reason for moving these?  You don't appear to be adding a
> use of them outside the .c file they were in before.

They are used in arch/powerpc/kvm/book3s_hv_nested.c. It was all in the
same patchset earlier, but during reorgazing the hcall into 3 separate patches,
this change remained here. May be I should move this change to the next patch
where it is used.

Thanks for your review.

Regards,
Bharata.