linux-kernel - [PATCH 4.14 062/118] KVM: PPC: Book3S PR: Fix WIMG handling under pHyp

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Message-Id: <20180115123419.241239982@linuxfoundation.org>
Date:   Mon, 15 Jan 2018 13:34:49 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Alexey Kardashevskiy <aik@...abs.ru>,
        Ruediger Oertel <ro@...e.de>, Greg Kurz <groug@...d.org>,
        Paul Mackerras <paulus@...abs.org>
Subject: [PATCH 4.14 062/118] KVM: PPC: Book3S PR: Fix WIMG handling under pHyp

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alexey Kardashevskiy <aik@...abs.ru>

commit 6c7d47c33ed323f14f2a3b8de925e831dbaa4e69 upstream.

Commit 96df226 ("KVM: PPC: Book3S PR: Preserve storage control bits")
added code to preserve WIMG bits but it missed 2 special cases:
- a magic page in kvmppc_mmu_book3s_64_xlate() and
- guest real mode in kvmppc_handle_pagefault().

For these ptes, WIMG was 0 and pHyp failed on these causing a guest to
stop in the very beginning at NIP=0x100 (due to bd9166ffe "KVM: PPC:
Book3S PR: Exit KVM on failed mapping").

According to LoPAPR v1.1 14.5.4.1.2 H_ENTER:

 The hypervisor checks that the WIMG bits within the PTE are appropriate
 for the physical page number else H_Parameter return. (For System Memory
 pages WIMG=0010, or, 1110 if the SAO option is enabled, and for IO pages
 WIMG=01**.)

This hence initializes WIMG to non-zero value HPTE_R_M (0x10), as expected
by pHyp.

[paulus@...abs.org - fix compile for 32-bit]

Fixes: 96df226 "KVM: PPC: Book3S PR: Preserve storage control bits"
Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>
Tested-by: Ruediger Oertel <ro@...e.de>
Reviewed-by: Greg Kurz <groug@...d.org>
Tested-by: Greg Kurz <groug@...d.org>
Signed-off-by: Paul Mackerras <paulus@...abs.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/powerpc/kvm/book3s_64_mmu.c |    1 +
 arch/powerpc/kvm/book3s_pr.c     |    2 ++
 2 files changed, 3 insertions(+)

--- a/arch/powerpc/kvm/book3s_64_mmu.c
+++ b/arch/powerpc/kvm/book3s_64_mmu.c
@@ -235,6 +235,7 @@ static int kvmppc_mmu_book3s_64_xlate(st
 		gpte->may_read = true;
 		gpte->may_write = true;
 		gpte->page_size = MMU_PAGE_4K;
+		gpte->wimg = HPTE_R_M;
 
 		return 0;
 	}
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -60,6 +60,7 @@ static void kvmppc_giveup_fac(struct kvm
 #define MSR_USER32 MSR_USER
 #define MSR_USER64 MSR_USER
 #define HW_PAGE_SIZE PAGE_SIZE
+#define HPTE_R_M   _PAGE_COHERENT
 #endif
 
 static bool kvmppc_is_split_real(struct kvm_vcpu *vcpu)
@@ -557,6 +558,7 @@ int kvmppc_handle_pagefault(struct kvm_r
 		pte.eaddr = eaddr;
 		pte.vpage = eaddr >> 12;
 		pte.page_size = MMU_PAGE_64K;
+		pte.wimg = HPTE_R_M;
 	}
 
 	switch (kvmppc_get_msr(vcpu) & (MSR_DR|MSR_IR)) {