From: "Jan Beulich" <JBeulich@suse.com>
To: Shuai Ruan <shuai.ruan@linux.intel.com>
Cc: andrew.cooper3@citrix.com, keir@xen.org, xen-devel@lists.xen.org
Subject: Re: [V4] x86/xsaves: calculate the xstate_comp_offsets base on xstate_bv
Date: Tue, 22 Mar 2016 04:53:02 -0600 [thread overview]
Message-ID: <56F1321E02000078000DF1CD@prv-mh.provo.novell.com> (raw)
In-Reply-To: <1458130372-7377-1-git-send-email-shuai.ruan@linux.intel.com>
>>> On 16.03.16 at 13:12, <shuai.ruan@linux.intel.com> wrote:
Please have patch subjects have [PATCH at their beginning.
> @@ -111,57 +111,70 @@ static int setup_xstate_features(bool_t bsp)
> for ( leaf = 2; leaf < xstate_features; leaf++ )
> {
> if ( bsp )
> + {
> cpuid_count(XSTATE_CPUID, leaf, &xstate_sizes[leaf],
> - &xstate_offsets[leaf], &tmp, &tmp);
> + &xstate_offsets[leaf], &ecx, &edx);
> + if ( ecx & XSTATE_ALIGN64 )
> + __set_bit(leaf, &xstate_align);
> + }
> else
> {
> cpuid_count(XSTATE_CPUID, leaf, &eax,
> - &ebx, &tmp, &tmp);
> + &ebx, &ecx, &edx);
> BUG_ON(eax != xstate_sizes[leaf]);
> BUG_ON(ebx != xstate_offsets[leaf]);
> + BUG_ON((ecx & XSTATE_ALIGN64) != test_bit(leaf, &xstate_align));
Neither side of the != seems correct: The left side would produce
0 or 2 (instead of 0 or 1), while the right side may produce any
non-zero value for truth.
> -static void __init setup_xstate_comp(void)
> +static void setup_xstate_comp(uint16_t *xstate_comp_offsets,
> + const u64 xstate_bv)
> {
> unsigned int i;
> + uint16_t offset;
>
> /*
> * The FP xstates and SSE xstates are legacy states. They are always
> * in the fixed offsets in the xsave area in either compacted form
> * or standard form.
> */
> - xstate_comp_offsets[0] = 0;
With the array now being uninitialized again you should no
longer delete this.
> xstate_comp_offsets[1] = XSAVE_SSE_OFFSET;
>
> xstate_comp_offsets[2] = FXSAVE_SIZE + XSAVE_HDR_SIZE;
>
> - for ( i = 3; i < xstate_features; i++ )
> + offset = xstate_comp_offsets[2];
> + for ( i = 2; i < xstate_features; i++ )
> {
> - xstate_comp_offsets[i] = xstate_comp_offsets[i - 1] +
> - (((1ul << i) & xfeature_mask)
> - ? xstate_sizes[i - 1] : 0);
> - ASSERT(xstate_comp_offsets[i] + xstate_sizes[i] <= xsave_cntxt_size);
> + if ( (1ul << i) & xstate_bv )
> + {
> + if ( test_bit(i, &xstate_align) )
> + offset = ROUNDUP(offset, 64);
> + xstate_comp_offsets[i] = offset;
> + offset += xstate_sizes[i];
> + ASSERT(offset <= xsave_cntxt_size);
This would seem to better go after the loop now that it's
independent of the loop variable. Also at least for this purpose
I think it would be better is "offset" was "unsigned int".
> static void *get_xsave_addr(struct xsave_struct *xsave,
> - unsigned int xfeature_idx)
> + const uint16_t *xstate_comp_offsets,
> + unsigned int xfeature_idx)
> {
> if ( !((1ul << xfeature_idx) & xsave->xsave_hdr.xstate_bv) )
> return NULL;
>
> - return (void *)xsave + (xsave_area_compressed(xsave)
> - ? xstate_comp_offsets
> - : xstate_offsets)[xfeature_idx];
> + return (void *)xsave + ( xsave_area_compressed(xsave) ?
> + xstate_comp_offsets[xfeature_idx] :
> + xstate_offsets[xfeature_idx] );
Stray blanks inside the parentheses.
> void expand_xsave_states(struct vcpu *v, void *dest, unsigned int size)
> {
> struct xsave_struct *xsave = v->arch.xsave_area;
> + uint16_t xstate_comp_offsets[sizeof(xfeature_mask)*8];
There's no point in prefixing a local variable in this file with xstate_.
And the same goes for the function parameters earlier on.
> @@ -172,6 +185,8 @@ void expand_xsave_states(struct vcpu *v, void *dest, unsigned int size)
> }
>
> ASSERT(xsave_area_compressed(xsave));
> + setup_xstate_comp(xstate_comp_offsets, xstate_bv);
Don't you need to use xcomp_bv here? That's what "Extended
Region of an XSAVE Area" in SDM Vol 1 suggests to me.
> @@ -222,6 +238,7 @@ void compress_xsave_states(struct vcpu *v, const void *src, unsigned int size)
> /* Set XSTATE_BV and XCOMP_BV. */
> xsave->xsave_hdr.xstate_bv = xstate_bv;
> xsave->xsave_hdr.xcomp_bv = v->arch.xcr0_accum | XSTATE_COMPACTION_ENABLED;
> + setup_xstate_comp(xstate_comp_offsets, xstate_bv);
Same here then I think.
Jan
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next prev parent reply other threads:[~2016-03-22 10:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-16 12:12 [V4] x86/xsaves: calculate the xstate_comp_offsets base on xstate_bv Shuai Ruan
2016-03-22 10:53 ` Jan Beulich [this message]
2016-03-23 1:28 ` Shuai Ruan
[not found] ` <20160323012803.GA4131@shuai.ruan@linux.intel.com>
2016-03-23 3:28 ` Shuai Ruan
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