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a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2025042001; t=1745570107; bh=FN/DKU8Mk2Q9Xof2Rumm+93wLI4a8v+UmrLXGE1N9mk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L78zoZAAN4f887y6qrYsRv1om8NzU+UWXr3Vc5HlTTSXUohwqXnXnQojJBw9b1s9T h86xOvwIJB6Ua8meWZlAGHT+h0th53l96xPbayjpOKZ4DjyHxqkGpydO8o/0KivYn/ jdmHXS+sQqnMkJPFn7dB5i5Yyfy1DYtABR6j7h99DUMuLqt/k17vF2jb+38yQcRdEV G9ngF24E4Kjj7fU2hIpR+Ghr6tgUOovBiIhQZcV+qhdz3Vedm6AWFYqyxgevLN4POO UVTWdh/p6/hvKNjFY4TLjPK6aHrVKvmhjHc4zWe61CNbkTMmx2vkewcubTz2h2/90a wIeCZ3lZzhmcw== From: "Xin Li (Intel)" To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-hyperv@vger.kernel.org, virtualization@lists.linux.dev, linux-pm@vger.kernel.org, linux-edac@vger.kernel.org, xen-devel@lists.xenproject.org, linux-acpi@vger.kernel.org, linux-hwmon@vger.kernel.org, netdev@vger.kernel.org, platform-driver-x86@vger.kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, acme@kernel.org, jgross@suse.com, andrew.cooper3@citrix.com, peterz@infradead.org, namhyung@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, kan.liang@linux.intel.com, wei.liu@kernel.org, ajay.kaher@broadcom.com, bcm-kernel-feedback-list@broadcom.com, tony.luck@intel.com, pbonzini@redhat.com, vkuznets@redhat.com, seanjc@google.com, luto@kernel.org, boris.ostrovsky@oracle.com, kys@microsoft.com, haiyangz@microsoft.com, decui@microsoft.com, dapeng1.mi@linux.intel.com Subject: [PATCH v3 09/14] x86/xen/msr: Remove calling native_{read,write}_msr{,_safe}() in pmu_msr_{read,write}() Date: Fri, 25 Apr 2025 01:34:32 -0700 Message-ID: <20250425083442.2390017-10-xin@zytor.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250425083442.2390017-1-xin@zytor.com> References: <20250425083442.2390017-1-xin@zytor.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @zytor.com) X-ZM-MESSAGEID: 1745570153736019000 Content-Type: text/plain; charset="utf-8" hpa found that pmu_msr_write() is actually a completely pointless function [1]: all it does is shuffle some arguments, then calls pmu_msr_chk_emulated() and if it returns true AND the emulated flag is clear then does *exactly the same thing* that the calling code would have done if pmu_msr_write() itself had returned true. And pmu_msr_read() does the equivalent stupidity. Remove the calls to native_{read,write}_msr{,_safe}() within pmu_msr_{read,write}(). Instead reuse the existing calling code that decides whether to call native_{read,write}_msr{,_safe}() based on the return value from pmu_msr_{read,write}(). Consequently, eliminate the need to pass an error pointer to pmu_msr_{read,write}(). While at it, refactor pmu_msr_write() to take the MSR value as a u64 argument, replacing the current dual u32 arguments, because the dual u32 arguments were only used to call native_write_msr{,_safe}(), which has now been removed. [1]: https://lore.kernel.org/lkml/0ec48b84-d158-47c6-b14c-3563fd14bcc4@zyto= r.com/ Suggested-by: H. Peter Anvin (Intel) Sign-off-by: Xin Li (Intel) Reviewed-by: Dapeng Mi Reviewed-by: Juergen Gross --- Change in v3: *) Rename pmu_msr_{read,write}() to pmu_msr_{read,write}_emulated() (Dapeng Mi). *) Fix a pmu_msr_read() callsite with wrong arguments (Dapeng Mi). --- arch/x86/xen/enlighten_pv.c | 8 ++++++-- arch/x86/xen/pmu.c | 27 ++++----------------------- arch/x86/xen/xen-ops.h | 4 ++-- 3 files changed, 12 insertions(+), 27 deletions(-) diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index 846b5737d320..61e51a970f3c 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -1090,7 +1090,7 @@ static u64 xen_do_read_msr(unsigned int msr, int *err) { u64 val =3D 0; /* Avoid uninitialized value for safe variant. */ =20 - if (pmu_msr_read(msr, &val, err)) + if (pmu_msr_read_emulated(msr, &val)) return val; =20 if (err) @@ -1132,6 +1132,8 @@ static void set_seg(unsigned int which, unsigned int = low, unsigned int high, static void xen_do_write_msr(unsigned int msr, unsigned int low, unsigned int high, int *err) { + u64 val; + switch (msr) { case MSR_FS_BASE: set_seg(SEGBASE_FS, low, high, err); @@ -1158,7 +1160,9 @@ static void xen_do_write_msr(unsigned int msr, unsign= ed int low, break; =20 default: - if (!pmu_msr_write(msr, low, high, err)) { + val =3D (u64)high << 32 | low; + + if (!pmu_msr_write_emulated(msr, val)) { if (err) *err =3D native_write_msr_safe(msr, low, high); else diff --git a/arch/x86/xen/pmu.c b/arch/x86/xen/pmu.c index 9c1682af620a..b6557f2d1a2e 100644 --- a/arch/x86/xen/pmu.c +++ b/arch/x86/xen/pmu.c @@ -313,37 +313,18 @@ static bool pmu_msr_chk_emulated(unsigned int msr, ui= nt64_t *val, bool is_read, return true; } =20 -bool pmu_msr_read(unsigned int msr, uint64_t *val, int *err) +bool pmu_msr_read_emulated(u32 msr, u64 *val) { bool emulated; =20 - if (!pmu_msr_chk_emulated(msr, val, true, &emulated)) - return false; - - if (!emulated) { - *val =3D err ? native_read_msr_safe(msr, err) - : native_read_msr(msr); - } - - return true; + return pmu_msr_chk_emulated(msr, val, true, &emulated) && emulated; } =20 -bool pmu_msr_write(unsigned int msr, uint32_t low, uint32_t high, int *err) +bool pmu_msr_write_emulated(u32 msr, u64 val) { - uint64_t val =3D ((uint64_t)high << 32) | low; bool emulated; =20 - if (!pmu_msr_chk_emulated(msr, &val, false, &emulated)) - return false; - - if (!emulated) { - if (err) - *err =3D native_write_msr_safe(msr, low, high); - else - native_write_msr(msr, low, high); - } - - return true; + return pmu_msr_chk_emulated(msr, &val, false, &emulated) && emulated; } =20 static u64 xen_amd_read_pmc(int counter) diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h index 735f58780704..163e03e33089 100644 --- a/arch/x86/xen/xen-ops.h +++ b/arch/x86/xen/xen-ops.h @@ -274,8 +274,8 @@ void xen_pmu_finish(int cpu); static inline void xen_pmu_init(int cpu) {} static inline void xen_pmu_finish(int cpu) {} #endif -bool pmu_msr_read(unsigned int msr, uint64_t *val, int *err); -bool pmu_msr_write(unsigned int msr, uint32_t low, uint32_t high, int *err= ); +bool pmu_msr_read_emulated(u32 msr, u64 *val); +bool pmu_msr_write_emulated(u32 msr, u64 val); int pmu_apic_update(uint32_t reg); u64 xen_read_pmc(int counter); =20 --=20 2.49.0