0003-x86-time-prevent-overflow-with-high-frequency-TSCs.patch


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From 65bf12135f618614bbf44626fba1c20ca8d1a127 Mon Sep 17 00:00:00 2001
From: Neowutran <xen@neowutran.ovh>
Date: Tue, 20 Dec 2022 13:51:42 +0100
Subject: [PATCH 03/61] x86/time: prevent overflow with high frequency TSCs

Make sure tsc_khz is promoted to a 64-bit type before multiplying by
1000 to avoid an 'overflow before widen' bug. Otherwise just above
4.294GHz the value will overflow. Processors with clocks this high are
now in production and require this to work correctly.

Signed-off-by: Neowutran <xen@neowutran.ovh>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: ad15a0a8ca2515d8ac58edfc0bc1d3719219cb77
master date: 2022-12-19 11:34:16 +0100
---
 xen/arch/x86/time.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
index 1daff92dca..db0b149ec6 100644
--- a/xen/arch/x86/time.c
+++ b/xen/arch/x86/time.c
@@ -2490,7 +2490,7 @@ int tsc_set_info(struct domain *d,
     case TSC_MODE_ALWAYS_EMULATE:
         d->arch.vtsc_offset = get_s_time() - elapsed_nsec;
         d->arch.tsc_khz = gtsc_khz ?: cpu_khz;
-        set_time_scale(&d->arch.vtsc_to_ns, d->arch.tsc_khz * 1000);
+        set_time_scale(&d->arch.vtsc_to_ns, d->arch.tsc_khz * 1000UL);
 
         /*
          * In default mode use native TSC if the host has safe TSC and
-- 
2.40.0