From nobody Sun Feb 8 02:41:11 2026 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8E433326931 for ; Thu, 13 Nov 2025 22:16:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763072211; cv=none; b=bwExKWmRpJu/V3qOd3q8uFySolwV28cqv5ZFjPyQ6mYR9HoD5EYETOqpdqRHVn3hWOIqp9cjS7IgbaeyMWvU/8O8dkaH+2paT5Z7wv+hAmcjsnTeNl28Lw5QEhUNFpknXEWWFOWf+pPKp4POCpFkVuxnuSUxxM2U61/etOFPH40= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763072211; c=relaxed/simple; bh=2kopUC4g9/xhmTC6tdsbn2Hz2t/yvA1KL42sg9IjKrk=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=BRTHev8H4ILEZmohzJ0EIfpH6aHZiv8zNwINYvJ14MKdLKz8zHOZc3qE+GlkUTUg1Ymi3nVfEDnY5KKVWNg/sawwvDzHLTpsQ4b5RJzGZT1aP4Co5cTcJC8GmxmnVvZs0dzkk/V7hZ9EOmj9/VB3W+bjO4GRVe8OFMc27vKibzw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=HN+V9lHG; arc=none smtp.client-ip=209.85.216.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="HN+V9lHG" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-343d73e159aso2640552a91.3 for ; Thu, 13 Nov 2025 14:16:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1763072207; x=1763677007; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=uLGpD5u1+xNmrNIiKbq+lQKqzP4N6LiuHe2X/eWaHM8=; b=HN+V9lHGD1HLqFboRq0oX6SBPUBNwVwcuhk5+3Qici9Tc1xr+y98xyfGRyfeSsBeVC aMBL9bIRrY9TQx/wg9fr/XzUlalzYliEqg5H2ToVeDmX3TKGgRKIbK+iBc9OzpHivR/Z 77a8HihsvQnjSu2RJKnBLdeqOw1/u6vSOYmoHkemcQz6EnFa6X+YiaeSOIt6tuKAZhXL cvKXlBsNJjkpxeXlg0QIKBNVa8zSYD5PZAu5GzcRsf2eAGt7j7fIFaSDfd0L8hZ8RUqo iYesq3lpDSzGYvEsoKxf/M6FGnQPAonBL6XmN2l5fSeB9s3oap8tBpKM+qJM9PbfoqT9 00Vw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1763072207; x=1763677007; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=uLGpD5u1+xNmrNIiKbq+lQKqzP4N6LiuHe2X/eWaHM8=; b=hTH9WXkpOowieNr+oK23HBeAfVJT0Bu8asoq9cZReCenJT1nWG/WXtDvJbjj4HVHc0 y88IjYnbAO0+J4K3wpE+tx6lpkQRVAW98IX8IydIKF/uy96HWuKvLNe0BTl9CGx6Xl21 XSyuIRueWoJjvnzNuw379K52aCKN3GHYmccuLZqT4Obc947vpupZDhihywV2f3BgRdJ3 jPhlkViV+90qdlNi2SfNqxygTgnB5oKK8+UOf29+BWBPlngbasWK+0iRVXB3sZkOKOGB 92h7KcesobLReijpWN7jFxGkS936IT7KerMsnGMXAqx+rOJtS0/+afO8QI5iRQERDvU6 2hBg== X-Forwarded-Encrypted: i=1; AJvYcCVHyPp+CJaUFR663YwzHllgpqf82p9jpY1YWvBzOxQCbrIGrJ5w5sJm5R3UerZhP8MHywMPczkp2D1u8Dg=@vger.kernel.org X-Gm-Message-State: AOJu0Yxu2IDWkieN19+8TedHCUWmRE+VojZC/EsmgkHq4h6wkKR6jszr X8hmAmzoShe5jweBfsQSOME4nU9DGHnjH2pMQvVzClGErFo28mCfSWELTjseCRVL0xc5DMjhC7g Am9wbJQ== X-Google-Smtp-Source: AGHT+IFcrWlYKwQtODUYyVSrZZl8AzPGS9xCGKenvs4ErgLoUW3lBmBduiKScfbuEVOMp6q0ZtzrEWY6quI= X-Received: from pjbeu11.prod.google.com ([2002:a17:90a:f94b:b0:338:3e6b:b835]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:564f:b0:340:f422:fc76 with SMTP id 98e67ed59e1d1-343f99abe95mr900158a91.0.1763072206760; Thu, 13 Nov 2025 14:16:46 -0800 (PST) Reply-To: Sean Christopherson Date: Thu, 13 Nov 2025 14:16:41 -0800 In-Reply-To: <20251113221642.1673023-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251113221642.1673023-1-seanjc@google.com> X-Mailer: git-send-email 2.52.0.rc1.455.g30608eb744-goog Message-ID: <20251113221642.1673023-2-seanjc@google.com> Subject: [PATCH 1/2] KVM: SVM: Rename "fault_address" to "gpa" in npf_interception() From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Rename "fault_address" to "gpa" in KVM's #NPF handler and track it as a gpa_t to more precisely document what type of address is being captured, and because "gpa" is much more succinct. No functional change intended. Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/svm.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index fc42bcdbb520..1fd097e8240e 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1857,8 +1857,8 @@ static int npf_interception(struct kvm_vcpu *vcpu) struct vcpu_svm *svm =3D to_svm(vcpu); int rc; =20 - u64 fault_address =3D svm->vmcb->control.exit_info_2; u64 error_code =3D svm->vmcb->control.exit_info_1; + gpa_t gpa =3D svm->vmcb->control.exit_info_2; =20 /* * WARN if hardware generates a fault with an error code that collides @@ -1872,14 +1872,14 @@ static int npf_interception(struct kvm_vcpu *vcpu) if (sev_snp_guest(vcpu->kvm) && (error_code & PFERR_GUEST_ENC_MASK)) error_code |=3D PFERR_PRIVATE_ACCESS; =20 - trace_kvm_page_fault(vcpu, fault_address, error_code); - rc =3D kvm_mmu_page_fault(vcpu, fault_address, error_code, + trace_kvm_page_fault(vcpu, gpa, error_code); + rc =3D kvm_mmu_page_fault(vcpu, gpa, error_code, static_cpu_has(X86_FEATURE_DECODEASSISTS) ? svm->vmcb->control.insn_bytes : NULL, svm->vmcb->control.insn_len); =20 if (rc > 0 && error_code & PFERR_GUEST_RMP_MASK) - sev_handle_rmp_fault(vcpu, fault_address, error_code); + sev_handle_rmp_fault(vcpu, gpa, error_code); =20 return rc; } --=20 2.52.0.rc1.455.g30608eb744-goog From nobody Sun Feb 8 02:41:11 2026 Received: from mail-pj1-f73.google.com (mail-pj1-f73.google.com [209.85.216.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A80E9326932 for ; Thu, 13 Nov 2025 22:16:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763072211; cv=none; b=ddyZCYpvUh5qtMLauRjkz03OI72NfuDkvb7BdfPSrh8+04iOC2jlSPHTSOt64VsRjC7y6/eDOoK/1zdPcKKQ7jYKwvoXHvFzX1lwDmBQOidbYE8KLj+mEX4LEgF7iPHt0zzQA36Ne0/KMeSclSn+OaJuA+/YZpg7DD4klIyUtek= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763072211; c=relaxed/simple; bh=YrPvvC78DcVV+WD3Lxn16NH8QR1mrcpNHdW/kFJpgoI=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=ckmg8mbbz28yMvdof1q1UNYYHx6nrBlgreGt1dJ0q/fTt7XhG4cF4iHpGu4FVycX2TTVSH/S3173x5U6d9jF8Brb1fKhoet+jxYBwNn1giAEYOFmNBlmXrjGg3g7MzlS9mpHaXrDkfqCtggIuMGiGAMgDh6yRYlRLeilUoId9+c= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=fzkyU5kv; arc=none smtp.client-ip=209.85.216.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="fzkyU5kv" Received: by mail-pj1-f73.google.com with SMTP id 98e67ed59e1d1-343fb64cea6so281653a91.3 for ; Thu, 13 Nov 2025 14:16:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1763072209; x=1763677009; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=XJ0so1Dc/Tcjqx77iXrmBHBcGNpRLjI2rEqnI8s+KfE=; b=fzkyU5kvA4f8WPMHFJMKMSs0fAnk0biLDhdNmBhWELR5jNzqy6TW+39DPuGHlevh1r xKxicCcZZlmazKI0hNLxNO58cL6l0KOcDNToEJXCz3f6OFm+1bmgE30Gal9kZyNcluhY RcQsLDNSYrosJg5DXDC0kt6sLVrDgd+1grDsyfJg/5fenUmwoGsPUiYJCxPBz8aTElji I/VQoZyRX/X9BcxDWjqQutp5MF7iizHdt7/udxrbDjVsxX9P1dDgDm4k7ukAvWb54PkE e0t/ggG/pSf2NsbqLeCUDlWh+eoy99LkON2D/OyVmBThq8Y6pqbdgtTdQ+RgUsH913Jp ZEYA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1763072209; x=1763677009; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=XJ0so1Dc/Tcjqx77iXrmBHBcGNpRLjI2rEqnI8s+KfE=; b=SADNkwrwM6AGV3oe38rBc/h51YaGkoXMWRIuFygsqFJq3pcv+OGfi2QmfOumB5pZxx pWod9knrF7V5v7WGaRYKt6Opp4vIRmDut7uB9Wtpw8GB/v3zTwMiRssbIdfxY07VJ13/ dv2K0zwQ9ry3yud+KX1++KQ67O2+olrsk8pbWyqCN6Dn/xYIcliw+69cPpIHkeeL4KEJ d3HuxAGvBygi/8a5KXmZruawuy3y+ZXazvx2E45gd5rPzQrZwQn0ofBTevv+BItj4M3U ZINDzZjAhsSmg8Sv91GROIg2AtKdGMfTBU0xx1F4iuYtkd3PUWtAnghPhApSVFuPaYVe Rp1Q== X-Forwarded-Encrypted: i=1; AJvYcCUatKcd6f8QcEJYsOus/41D8BEdXrtxZHtM6VvghHy94y1add8tUVGgxDm62O0j9LnTr9vhc5WDpbttKig=@vger.kernel.org X-Gm-Message-State: AOJu0YwYD/MjjrYZhLlNgS/yGepmkzDi+XwFEKpJvDV+tbq//NmYKRr+ 16FKGRSAMRs2UVP25LRGoXFR859KNhH5Wv1P7ft/552b2h/zU3KC8imXaUtbsnvGEz+weEwbeHp Ztsrdpg== X-Google-Smtp-Source: AGHT+IFTcvFDNI+4BP0QllZu5ahML/elMMLsl7V/HGS9DicfOfSCUPbFdET+/m0IHyoe01XmI2jprwp8b0s= X-Received: from pjbdj6.prod.google.com ([2002:a17:90a:d2c6:b0:33e:2d15:8e39]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:2685:b0:33b:b078:d6d3 with SMTP id 98e67ed59e1d1-343fa62bf74mr752300a91.23.1763072209003; Thu, 13 Nov 2025 14:16:49 -0800 (PST) Reply-To: Sean Christopherson Date: Thu, 13 Nov 2025 14:16:42 -0800 In-Reply-To: <20251113221642.1673023-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251113221642.1673023-1-seanjc@google.com> X-Mailer: git-send-email 2.52.0.rc1.455.g30608eb744-goog Message-ID: <20251113221642.1673023-3-seanjc@google.com> Subject: [PATCH 2/2] KVM: SVM: Add support for expedited writes to the fast MMIO bus From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Wire up SVM's #NPF handler to fast MMIO. While SVM doesn't provide a dedicated exit reason, it's trivial to key off PFERR_RSVD_MASK. Like VMX, restrict the fast path to L1 to avoid having to deal with nGPA=3D>GPA translations. For simplicity, use the fast path if and only if the next RIP is known. While KVM could utilize EMULTYPE_SKIP, doing so would require additional logic to deal with SEV guests, e.g. to go down the slow path if the instruction buffer is empty. All modern CPUs support next RIP, and in practice the next RIP will be available for any guest fast path. Copy+paste the kvm_io_bus_write() + trace_kvm_fast_mmio() logic even though KVM would ideally provide a small helper, as such a helper would need to either be a macro or non-inline to avoid including trace.h in a header (trace.h must not be included by x86.c prior to CREATE_TRACE_POINTS being defined). Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/svm.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 1fd097e8240e..9fce0f46f79e 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1852,6 +1852,9 @@ static int pf_interception(struct kvm_vcpu *vcpu) svm->vmcb->control.insn_len); } =20 +static int svm_check_emulate_instruction(struct kvm_vcpu *vcpu, int emul_t= ype, + void *insn, int insn_len); + static int npf_interception(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm =3D to_svm(vcpu); @@ -1869,6 +1872,24 @@ static int npf_interception(struct kvm_vcpu *vcpu) if (WARN_ON_ONCE(error_code & PFERR_SYNTHETIC_MASK)) error_code &=3D ~PFERR_SYNTHETIC_MASK; =20 + /* + * Expedite fast MMIO kicks if the next RIP is known and KVM is allowed + * emulate a page fault, e.g. skipping the current instruction is wrong + * if the #NPF occurred while vectoring an event. + */ + if ((error_code & PFERR_RSVD_MASK) && !is_guest_mode(vcpu)) { + const int emul_type =3D EMULTYPE_PF | EMULTYPE_NO_DECODE; + + if (svm_check_emulate_instruction(vcpu, emul_type, NULL, 0)) + return 1; + + if (nrips && svm->vmcb->control.next_rip && + !kvm_io_bus_write(vcpu, KVM_FAST_MMIO_BUS, gpa, 0, NULL)) { + trace_kvm_fast_mmio(gpa); + return kvm_skip_emulated_instruction(vcpu); + } + } + if (sev_snp_guest(vcpu->kvm) && (error_code & PFERR_GUEST_ENC_MASK)) error_code |=3D PFERR_PRIVATE_ACCESS; =20 --=20 2.52.0.rc1.455.g30608eb744-goog