... to improve the legibility of the following fix.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Roger Pau Monné <roger.pau@citrix.com>

Best reviewed with `git show --ignore-all-space`
---
 xen/arch/x86/xstate.c | 131 ++++++++++++++++++++++--------------------
 1 file changed, 68 insertions(+), 63 deletions(-)

diff --git a/xen/arch/x86/xstate.c b/xen/arch/x86/xstate.c
index e990abc9d18c..384f78bd5281 100644
--- a/xen/arch/x86/xstate.c
+++ b/xen/arch/x86/xstate.c
@@ -407,19 +407,19 @@ void xrstor(struct vcpu *v, uint64_t mask)
      */
     for ( prev_faults = faults = 0; ; prev_faults = faults )
     {
-        switch ( __builtin_expect(ptr->fpu_sse.x[FPU_WORD_SIZE_OFFSET], 8) )
-        {
-            BUILD_BUG_ON(sizeof(faults) != 4); /* Clang doesn't support %z in asm. */
-#define _xrstor(insn) \
-        asm volatile ( "1: .byte " insn "\n" \
-                       "3:\n" \
-                       "   .section .fixup,\"ax\"\n" \
-                       "2: incl %[faults]\n" \
-                       "   jmp 3b\n" \
-                       "   .previous\n" \
-                       _ASM_EXTABLE(1b, 2b) \
-                       : [mem] "+m" (*ptr), [faults] "+g" (faults) \
-                       : [lmask] "a" (lmask), [hmask] "d" (hmask), \
+    switch ( __builtin_expect(ptr->fpu_sse.x[FPU_WORD_SIZE_OFFSET], 8) )
+    {
+        BUILD_BUG_ON(sizeof(faults) != 4); /* Clang doesn't support %z in asm. */
+#define _xrstor(insn)                                               \
+        asm volatile ( "1: .byte " insn "\n"                        \
+                       "3:\n"                                       \
+                       "   .section .fixup,\"ax\"\n"                \
+                       "2: incl %[faults]\n"                        \
+                       "   jmp 3b\n"                                \
+                       "   .previous\n"                             \
+                       _ASM_EXTABLE(1b, 2b)                         \
+                       : [mem] "+m" (*ptr), [faults] "+g" (faults)  \
+                       : [lmask] "a" (lmask), [hmask] "d" (hmask),  \
                          [ptr] "D" (ptr) )
 
 #define XRSTOR(pfx) \
@@ -437,62 +437,67 @@ void xrstor(struct vcpu *v, uint64_t mask)
         else \
             _xrstor(pfx "0x0f,0xae,0x2f") /* xrstor */
 
-        default:
-            XRSTOR("0x48,");
-            break;
-        case 4: case 2:
-            XRSTOR("");
-            break;
+    default:
+        XRSTOR("0x48,");
+        break;
+
+    case 4: case 2:
+        XRSTOR("");
+        break;
+
 #undef XRSTOR
 #undef _xrstor
-        }
-        if ( likely(faults == prev_faults) )
-            break;
+    }
+
+    if ( likely(faults == prev_faults) )
+        break;
+
 #ifndef NDEBUG
-        gprintk(XENLOG_WARNING, "fault#%u: mxcsr=%08x\n",
-                faults, ptr->fpu_sse.mxcsr);
-        gprintk(XENLOG_WARNING, "xs=%016lx xc=%016lx\n",
-                ptr->xsave_hdr.xstate_bv, ptr->xsave_hdr.xcomp_bv);
-        gprintk(XENLOG_WARNING, "r0=%016lx r1=%016lx\n",
-                ptr->xsave_hdr.reserved[0], ptr->xsave_hdr.reserved[1]);
-        gprintk(XENLOG_WARNING, "r2=%016lx r3=%016lx\n",
-                ptr->xsave_hdr.reserved[2], ptr->xsave_hdr.reserved[3]);
-        gprintk(XENLOG_WARNING, "r4=%016lx r5=%016lx\n",
-                ptr->xsave_hdr.reserved[4], ptr->xsave_hdr.reserved[5]);
+    gprintk(XENLOG_WARNING, "fault#%u: mxcsr=%08x\n",
+            faults, ptr->fpu_sse.mxcsr);
+    gprintk(XENLOG_WARNING, "xs=%016lx xc=%016lx\n",
+            ptr->xsave_hdr.xstate_bv, ptr->xsave_hdr.xcomp_bv);
+    gprintk(XENLOG_WARNING, "r0=%016lx r1=%016lx\n",
+            ptr->xsave_hdr.reserved[0], ptr->xsave_hdr.reserved[1]);
+    gprintk(XENLOG_WARNING, "r2=%016lx r3=%016lx\n",
+            ptr->xsave_hdr.reserved[2], ptr->xsave_hdr.reserved[3]);
+    gprintk(XENLOG_WARNING, "r4=%016lx r5=%016lx\n",
+            ptr->xsave_hdr.reserved[4], ptr->xsave_hdr.reserved[5]);
 #endif
-        switch ( faults )
+
+    switch ( faults )
+    {
+    case 1: /* Stage 1: Reset state to be loaded. */
+        ptr->xsave_hdr.xstate_bv &= ~mask;
+        /*
+         * Also try to eliminate fault reasons, even if this shouldn't be
+         * needed here (other code should ensure the sanity of the data).
+         */
+        if ( ((mask & X86_XCR0_SSE) ||
+              ((mask & X86_XCR0_YMM) &&
+               !(ptr->xsave_hdr.xcomp_bv & XSTATE_COMPACTION_ENABLED))) )
+            ptr->fpu_sse.mxcsr &= mxcsr_mask;
+        if ( v->arch.xcr0_accum & XSTATE_XSAVES_ONLY )
         {
-        case 1: /* Stage 1: Reset state to be loaded. */
-            ptr->xsave_hdr.xstate_bv &= ~mask;
-            /*
-             * Also try to eliminate fault reasons, even if this shouldn't be
-             * needed here (other code should ensure the sanity of the data).
-             */
-            if ( ((mask & X86_XCR0_SSE) ||
-                  ((mask & X86_XCR0_YMM) &&
-                   !(ptr->xsave_hdr.xcomp_bv & XSTATE_COMPACTION_ENABLED))) )
-                ptr->fpu_sse.mxcsr &= mxcsr_mask;
-            if ( v->arch.xcr0_accum & XSTATE_XSAVES_ONLY )
-            {
-                ptr->xsave_hdr.xcomp_bv &= this_cpu(xcr0) | this_cpu(xss);
-                ptr->xsave_hdr.xstate_bv &= ptr->xsave_hdr.xcomp_bv;
-                ptr->xsave_hdr.xcomp_bv |= XSTATE_COMPACTION_ENABLED;
-            }
-            else
-            {
-                ptr->xsave_hdr.xstate_bv &= this_cpu(xcr0);
-                ptr->xsave_hdr.xcomp_bv = 0;
-            }
-            memset(ptr->xsave_hdr.reserved, 0, sizeof(ptr->xsave_hdr.reserved));
-            continue;
-
-        case 2: /* Stage 2: Reset all state. */
-            ptr->fpu_sse.mxcsr = MXCSR_DEFAULT;
-            ptr->xsave_hdr.xstate_bv = 0;
-            ptr->xsave_hdr.xcomp_bv = v->arch.xcr0_accum & XSTATE_XSAVES_ONLY
-                                      ? XSTATE_COMPACTION_ENABLED : 0;
-            continue;
+            ptr->xsave_hdr.xcomp_bv &= this_cpu(xcr0) | this_cpu(xss);
+            ptr->xsave_hdr.xstate_bv &= ptr->xsave_hdr.xcomp_bv;
+            ptr->xsave_hdr.xcomp_bv |= XSTATE_COMPACTION_ENABLED;
         }
+        else
+        {
+            ptr->xsave_hdr.xstate_bv &= this_cpu(xcr0);
+            ptr->xsave_hdr.xcomp_bv = 0;
+        }
+        memset(ptr->xsave_hdr.reserved, 0, sizeof(ptr->xsave_hdr.reserved));
+        continue;
+
+    case 2: /* Stage 2: Reset all state. */
+        ptr->fpu_sse.mxcsr = MXCSR_DEFAULT;
+        ptr->xsave_hdr.xstate_bv = 0;
+        ptr->xsave_hdr.xcomp_bv = v->arch.xcr0_accum & XSTATE_XSAVES_ONLY
+            ? XSTATE_COMPACTION_ENABLED : 0;
+        continue;
+    }
 
         domain_crash(current->domain);
         return;
-- 
2.39.5

On 30.12.2025 14:54, Andrew Cooper wrote:
> ... to improve the legibility of the following fix.

... wanting to replace the for() with an open-coded form of a loop. Which
is fine, but could have done with saying here.

> No functional change.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

Acked-by: Jan Beulich <jbeulich@suse.com>

Jan