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Mon, 27 May 2024 05:57:52 -0700 (PDT) Message-ID: Date: Mon, 27 May 2024 14:57:51 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 09/13] xen/bitops: Replace find_first_set_bit() with ffsl() - 1 Content-Language: en-US To: Andrew Cooper Cc: =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= , Wei Liu , Stefano Stabellini , Julien Grall , Volodymyr Babchuk , Bertrand Marquis , Michal Orzel , Oleksii Kurochko , Shawn Anastasio , "consulting @ bugseng . com" , Simone Ballarin , Federico Serafini , Nicola Vetrini , Xen-devel References: <20240524200338.1232391-1-andrew.cooper3@citrix.com> <20240524200338.1232391-10-andrew.cooper3@citrix.com> From: Jan Beulich Autocrypt: addr=jbeulich@suse.com; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL In-Reply-To: <20240524200338.1232391-10-andrew.cooper3@citrix.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 24.05.2024 22:03, Andrew Cooper wrote: > --- a/xen/arch/x86/hvm/hpet.c > +++ b/xen/arch/x86/hvm/hpet.c > @@ -335,7 +335,7 @@ static void timer_sanitize_int_route(HPETState *h, unsigned int tn) > * enabled pick the first irq. > */ > timer_config(h, tn) |= > - MASK_INSR(find_first_set_bit(timer_int_route_cap(h, tn)), > + MASK_INSR(ffsl(timer_int_route_cap(h, tn)) - 1, > HPET_TN_ROUTE); > } This can be just ffs(). > @@ -409,7 +409,7 @@ static int cf_check hpet_write( > { > bool active; > > - i = find_first_set_bit(new_val); > + i = ffsl(new_val) - 1; > if ( i >= HPET_TIMER_NUM ) > break; This in principle can be, too, but would require a little further care. > @@ -535,14 +535,14 @@ static int cf_check hpet_write( > /* stop/start timers whos state was changed by this write. */ > while (stop_timers) > { > - i = find_first_set_bit(stop_timers); > + i = ffsl(stop_timers) - 1; > __clear_bit(i, &stop_timers); > hpet_stop_timer(h, i, guest_time); > } > > while (start_timers) > { > - i = find_first_set_bit(start_timers); > + i = ffsl(start_timers) - 1; > __clear_bit(i, &start_timers); > hpet_set_timer(h, i, guest_time); > } Same here; in fact {start,stop}_timers are needlessly unsigned long in the first place. > --- a/xen/arch/x86/include/asm/pt-contig-markers.h > +++ b/xen/arch/x86/include/asm/pt-contig-markers.h > @@ -60,7 +60,7 @@ static bool pt_update_contig_markers(uint64_t *pt, unsigned int idx, > /* Step 1: Reduce markers in lower numbered entries. */ > while ( i ) > { > - b = find_first_set_bit(i); > + b = ffsl(i) - 1; > i &= ~(1U << b); Considering i's type and the immediately following expression, this again can easily be just ffs(). > --- a/xen/drivers/passthrough/amd/iommu_map.c > +++ b/xen/drivers/passthrough/amd/iommu_map.c > @@ -137,7 +137,7 @@ static void set_iommu_ptes_present(unsigned long pt_mfn, > ASSERT(!pde->u); > > if ( pde > table ) > - ASSERT(pde->ign0 == find_first_set_bit(pde - table)); > + ASSERT(pde->ign0 == ffsl(pde - table) - 1); pde pointing into the page starting at table, this can be ffs(), too. Preferably with at least the easy adjustments done: Reviewed-by: Jan Beulich Jan